Nghiên cứu mô bệnh học, hóa mô miễn dịch và một số yếu tố tiên lượng của sarcôm mô mềm thường gặp ttta

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF HEALTH
HANOI MEDICAL UNIVERSITY

HO DUC THUONG

INVESTIGATE HISTOPATHOLOGY,
IMMUNOHISTOCHEMISTRY AND SOME PROGNOSTIC
FACTORS OF COMMON SOFT TISSUE SARCOMAS

Major

: Biomedical Science (AnatomicalPathology-Forensic Pathology)

Code

: 9720101

SUMMARY OF MEDICAL PhD THESIS

HANOI – 2022


THE WORK HAS BEEN COMPLETED AT
HANOI MEDICAL UNIVERSITY

Supervisor:
Ass.Prof. LE DINH DOANH

Opponent 1: ...............................
Opponent 2: ...............................
Opponent 3: ...............................

The thesis will be defended at Board of Examiners of Hanoi Medical
University At: 14:00 Date: 10/ 09 / 20...

The thesis can be found at:
1. National library of Vietnam
2. Library of Hanoi Medical University


PUBLISHED RESEARCH PROJECTS RELATED
TO THE CONTENT OF THE THESIS
1.

2.

3.

4.

Ho Duc Thuong, Nguyen Thi Khuyen (2018), “Histopathological
characteristics and TFE3 expression of niche soft tissue sarcoma: Four
case studies at Viet Duc Hospital and reviewing medical literature”,
Vietnam Cancer Journal, Issue No. 5 - 2018, pp. 256-261.
Ho Duc Thuong, Le Dinh Roanh (2020), “Histological type
classification, expression of MDM2/CDK4 markers and some
prognostic factors of fatty sarcoma at Viet Duc Hospital”, Medical
Practice Journal, Issue No.1139, July 2020, pp. 74-77.
Ho Duc Thuong, Nguyen Thi Luan, Nguyen Sy Lanh, Le Dinh Roanh
(2020), “Histological characteristics, expression of STAT6 and CD34
markers in 62 isolated fibroid cases at Viet Duc Hospital” , Medical

Practice Journal, Issue No. 1139, July 2020, pp. 112-116.
Ho Duc Thuong, Nguyen Thi Quynh, Dao Thi Luan, Nguyen Sy Lanh,
Nguyen Duc Thang (2021), “Low-grade mucinous fibrosarcoma: A
case study at Viet Duc Hospital and a review of the medical literature”,
Vietnam Journal of Oncology, Issue No.1 - 2021, pp. 367-372.


1
INTRODUCTION
Soft tissue sarcomas (STS) are cancers of the connective tissue in
addition to bone except for lymphoid tissue, glial tissue, and supporting tissues
of organs. Compared with other cancers, STS are relatively rare. Accurate
diagnosis of histopathological type as well as subtype of STS is of great
significance, deciding treatment attitude and predicting disease prognosis.
Previously, the histopathological diagnosis of STS was based only on routine
histological techniques of Hematoxylin Eosin (HE) staining and some special
staining methods. Today, thanks to the help of modern techniques such as
immunohistochemistry (IHC) and molecular biology, the diagnosis of STS
has been improved. diagnose. The introduction of IHC is a revolution in the
diagnosis of pathology in general and in the diagnosis of STS in particular.
In recent times, with the appearance of many new molecularly significant
antibodies, IHC has shown an increasingly important role in diagnosing and
determining the histopathological type of STS.
So far, there are many classifications of STS, in which the Fourth World
Health Organization (WHO) classification of STS in 2013 has highlighted
the role of IHC and molecular biology in stool. histopathological type of
STS. In early 2020, the WHO's fifth classification of soft tissue and bone
tumors was born, in addition to adding some new histopathological types
and molecular biology, the classification also updated a new element. has
new prognostic significance of some common tumor types, dedifferentiated

liposarcomas, solitary fibrous tumors.
In terms of treatment, surgery is the first indication for STS, however,
it is difficult to remove the entire tumor, because the tumor often has
extensive local invasion, the tumor size is often large and varies with
anatomical position. This is also one of the important factors in the
prognosis of STS. For the above reasons, the project titled “ Investigate
histopathology, immunohistochemistry and some prognostic factors of
common soft tissue sarcomas” has been carried out for the following
purposes:
1. Study on histopathology and immunohistochemistry of soft
tissue sarcomas according to the classification of the WHO 2013.
2. Analysis of some macroscopic and microscopic factors with
prognostic significance of some common soft tissue sarcomas.
NEW CONTRIBUTIONS OF THE THESIS
1. This is the first study in Vietnam to apply histopathology, IHC in
the diagnosis of STS in peripheral and central locations according to the
classification of the WHO 2013.


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2. The results from the study show that:
The study classified the histopathological type on 363 cases of STS
with 11/12 groups of origin, of which the most common group was
fibroblastic /myofibroblastic sarcomas (29.2%), followed by adipocytic
sarcomas (26,20%); sarcomas of uncertain differentiation 14.9%;…; There
were no cases of perivascular tumour group. Extra-digestive GIST accounts
for 2.2% (8/363) of STSs in general and 5.9% (8/136) of retroperitonealintra-abdominal STSs. IHC not only plays an important role in the
histopathological classification of STSs, but some markers are also valuable
in determining the molecular nature of the tumor such as MDM2, CDK4,
INI1, MUC4, TFE3 , WT1, H3k27me3.

- The higher histological grading of STS according to FNCLCC and
Ki-67 grade is, the higher the rate of positive surgical resection (R1-R2)
with p < 0.05 is increased.
- The stratification of the risk of metastasis of malignant solitary
fibrous tumours (≥ 4 mitoses/10 HPF) in more than 50 cases: low risk 56%,
medium risk 34%, high risk 10%.
THE STRUCTURE OF THE THESIS
The thesis consists of 147 pages, including the following parts:
Introduction (2 pages), Chapter 1: Literature Overview (38 pages), Chapter
2: Research Subjects and Methods (21 pages); Chapter 3: Research results
(35 pages); Chapter 4: Discussion (48 pages); Conclusion (2 pages);
Recommendations (1 page). In the thesis, there are 36 tables, 6 charts and 2
figure. References have 222 documents (8 documents in Vietnamese and
214 documents in English). The appendix includes a list of patients,
illustrations, and sample research records.
CHAPTER 1. LITERATURE OVERVIEW
1.1. Research situation on soft tissue sarcoma in the world and in
Vietnam
Recent studies on molecular biology and IHC in the field of STS have
helped to diagnose the genetic nature of many histological types,
discovering many new histologic types from undifferentiated/unclassified
STSs, leading to the introduction of the new classification of STSs of the
WHO 2013 and more recently the WHO 2020. Studies on biochemical
markers IHC with molecular value is realized and increasingly applied in
diagnostic practice.


3
1.2. Histopathological classification of soft tissue sarcomas
The first globally accepted histopathological classification for STS

was the WHO classification (1969). Advances in IHC and molecular
biology have led to the creation of new classifications that better serve the
diagnosis, treatment, and prognosis. Up to now, there have been 05
classifications of STS of the WHO, the latest 02 classifications were born in
2013 and 2020.
1.2.1. Histological classification of soft tissue sarcomas of the 4th World
Health Organization (2013)
The WHO 2013 STS classification was born 11 years after the
previous classification. During that time there have been some changes in
the classification of STS, mainly based on the discovery of new genes in
differentiating tumor types. In addition, several new distinct morphological
types of tumor subtypes have been described along with novel alterations in
the genetic problem. Classification divides STS into 12 groups of origin:
adipocytic, fibroblastic/myofibroblastic, so-called fibrohistiocytic, smoothmuscle, perivascular, skeletal-muscle, vascular, chondro-osseous,
gastrointestinal stromal tumor (GIST), nerve sheath, uncertain
differentiation and unclassified/undifferentiated.
Some new points of the 2013 classification compared to the previous ones:
- Adipocytic tumours: The most notable change in this tumor
category is the removal of the term round cell liposarcoma, and the
classification of this tumor in the group of high-grade myxoid liposarcomas.
Mixed type liposarcomas have also been excluded from this classification
and are classified as dedifferentiated liposarcomas.
- Fibroblastic/myofibroblastic tumours: Dermatofibrosarcoma
Protuberans (DFSP) is closely related to giant cell fibroblastoma and is
included in the WHO 2013, both tumors had rearrangements of
chromosomes 17 and 22, which resulted in the formation of the mosaic
gene PDGFB-COL1A. DFSP is classified as a tumor that rarely
metastasizes (intermediate), although it has the potential to metastasize in
the presence of a fibrosarcomatous component (Dermatofibrosarcoma
Protuberans- variant Fibrosarcomatous - DFSP-FS). The subtypes of

hemangiopericytomas were eliminated and classified as solitary fibrous
tumours due to the discovery of the same NAB2-STAT6 gene. The WHO
2013 classification recognizes the close relationship between low-grade
fibromyxoid sarcoma and a subtype of sclerosing epithelioid fibrosarcoma.
- So-called fibrohistiocytic tumours: The term “malignant fibrous
histiocytomas” was dropped from the 2013 WHO classification. The term is


4
obsolete, it includes many types of tumors that now exist. can be precisely
classified as specific types of sarcomas. Unclassified/undifferentiated
sarcomas now have their own classification.
- Rhabdomyosarcoma: The classification of “sclerosing/spindle cell
rhabdomyosarcoma” was separated from embryonal rhabdomyosarcoma
due to the detection of genetic differences.
- Vascular tumours: A newly recognized term "pseudomyogenic
haemangioendothelioma"
(and
also
“epithelioid
sarcoma-like
haemangioendothelioma”) is included in this category.
- Gastrointestinal stromal tumour: For the first time, GIST was
included in the soft tissue tumour classification of the WHO (2013),
previously GIST belonged to the classification of digestive system tumours.
It is worth noting that in the GIST classification there is recognition of SDH
deficiency GIST.
- Tumours of uncertainly differentiation: There are 2 new groups
added to the 2013 classification: "Haemosidrotic fibrolipomatous tumour"
and “Phosphaturic mesenchymal tumor”. The term "primitive

neuroectodermal neoplasm" (PNET) (synonymous with Ewing's sarcoma)
has been dropped from this classification. This is to reduce complex
histological and genomic differences, similarity of names, PNETs of the
central nervous system, and female genital tract.
- Undifferentiated/unclassified sarcomas: This group of tumors is
new to the WHO 2013 classification, and is referred to as a tumor that cannot
be classified into any other class because it cannot be proven otherwise.
histological, IHC, or molecular biology.
1.2.2. Histological classification of soft tissue sarcomas of the 5th World
Health Organization (2020)
The fifth edition of the WHO's Classification of Bone and Soft
Tissue Tumors was published in early 2020, seven years after the fourth
edition. New updates on classification are based on new genetic databases,
prompting the introduction of several new histopathological subtypes and
regrouping of some tumor types. The chapter on soft tissue tumors in
particular includes the addition of recently described tumor types; In some
cases, more and more molecular biology research results are used to inform
the reclassification of soft tissue tumors or to change the nomenclature and
management of the disease. Despite the increasing contribution of
molecular biology, new classifications continue to emphasize the central
diagnostic role of morphology. In addition to introducing “new” soft tissue
tumor types, this classification also provides prognostic updates for familiar


5
tumors such as dedifferentiated liposarcomas and solitary fibrous tumours.
The classification also includes discussions focusing on a range of genetic
alterations recently described in soft tissue tumours. The past decade has
been full of new discoveries of gene fusions in rare soft tissue tumors.
These include genetic alterations that are relevant to diagnostic practice. An

example is the chapter on undifferentiated small round cell sarcomas; The
discovery of new gene fusions has led to the subtype of formerly "Ewinglike" sarcomas into new types with distinct clinical, morphological and
immunohistochemical manifestations.
1.3. The role of immunohistochemistry in the diagnosis of soft tissue
sarcoma
IHC is a special staining technique that uses specific antibodies to
determine the presence of antigens on a slice of tissue or on different types
of cells present in the tissue. The basic principle is that when applying a
tissue-specific antibody, if the antigen is present in the tissue, an antigenantibody combination reaction will occur. In the diagnosis of STS, IHC not
only detects the differentiation of tumor cells, helps to accurately classify
each histopathological type and distinguishes it from other cancers, but also
detects abnormal proteins. generated from combined genes due to tumorspecific translocations or abnormal proteins produced by mutations in some
genes involved in tumorigenesis. Therefore, although it is an immunological
technique, it reflects the lesion characteristics at the molecular level. Nowadays,
the introduction of automated IHC staining machines has improved the
technical quality. Many new studies on IHC and many new markers are
significant in the diagnosis of STS. In STS diagnostic practice, IHC can be
used with 3 main roles:
- Distinguish with benign lesions (pseudo-STS).
- Distinguish with non-sarcoma undifferentiated malignancies.
- Classification of sarcomas.
1.4. Prognosis of soft tissue sarcomas
1.4.1. Significant factors in the prognosis of soft tissue sarcoma
Prognostic factors include 3 main groups: patient-related factors,
tumor-related factors, and treatment-related factors. Some factors are
significant in the prognosis of STS such as: age, tumor location, tumor size,
surgical resection margin (R), histopathological type, histological grade,
TNM...
1.4.2. Ki-67 marker in the prognosis of soft tissue sarcoma
Several histological grading systems based on IHC have been

proposed, of which Ki-67 - a protein involved in cell proliferation - is the


6
most widely studied marker. Furthermore, this method shows high validity
and reproducibility in histological classification of STS by semiquantitative method. In addition, several studies have demonstrated that Ki67 expression level is an independent predictor of survival in STS.
1.4.3. Update on prognostic factors of some soft tissue sarcomas
according to WHO 2020
Table 1.3. WHO 2020 Classification: New concepts in nomenclature,
grade and risk factor stratification
Tumor type
What's new?
Malignant melanotic Change in nomenclature (formerly melanoma
nerve sheath tumour
Schwann cell tumor) to indicate clinical
malignancy
Dedifferentiated
Adverse effects of high histologic grade according
liposarcoma
to FNCLCC, as well as with muscle differentiation
(especially rhabdomyolysis) were noted.
Solitary fibrous tumor Prognostic model predicts risk of metastasis,
using patient age, mitotic rate, tumor size, and
necrosis
CHAPTER 2. RESEARCH SUBJECTS AND METHODS
2.1. Research subjects
2.1.1. Research subjects
The study was carried out on STS cases according to the classification
of the WHO 2013, at the Department of Pathology - Viet Duc Hospital,
from January 1, 2016 to December 31, 2020.

2.1.2. Selection criteria
The patient must meet all of the following criteria:
- Primary STSs of head and neck, extremities, trunk, retroperitoneum intra-abdominal, pleura - mediastinum.
- Type of specimen: Surgical specimen.
- There are templates and paraffin blocks for storage
- Tissue samples are sufficiently exploited, still have antigenicity
(based on staining of negative and positive controls), and tumor tissue
samples have enough IHC staining.
2.1.3. Exclusion criteria
- Tumors from bone, viscera or gastrointestinal tract invading soft tissue
- Needle biopsies
- Necrotic specimens do not meet the criteria for histopathology, IHC
or genetic analysis


7
- No more paraffin blocks or poor quality paraffin blocks
2.2. Research Methods
- Study design: The study was designed by cross-sectional descriptive
method.
- Research sample size: Selected 363 cases suitable for research
subjects.
- How to select research sample: All cases of STS satisfying the
selection criteria (2.1.2) and exclusion criteria (2.1.3) were selected into the
study sample.
2.3. Research contents
2.3.1. Research variables and indicators
2.3.1.1. Some clinical features
- Age: Percentage of age groups (<20; 20-39; 40-59; ≥ 60)
- Gender: Percentage of men and women in STS

- Location: Percentage of groups of STS sites
2.3.1.2. Histopathological and immunohistochemical features
- Based on the characteristics of the HE specimen, IHC and some
genetic analysis, to determine the histopathological type of STSs according
to the WHO’s Histological Classification of Soft Tissue Tumors in 2013.
Updated according to WHO 2020.
+ Type Histopathological WHO 2013 classification of STSs.
+ Percentage of histopathological types according to the origin of STS
+ Percentage of histopathological types according to groups of origin
+ Describe histopathological characteristics of some common and rare
types. Evaluation of histopathological characteristics on tumor cell
morphology, stromal, tumor structure, multiplication rate, activity, and cell
differentiation.
+ Expression rate of IHC markers by type or group of subtypes
+ Intensity reveals some imprints
+ The relationship of some IHC markers with histopathological type
+ Identify genetic characteristics of some cases
1.3.1.3. Some macroscopic and microscopic factors have prognostic
significance
- Size: Divide tumor size into 04 groups according to AJCC: ≤ 5 cm;
>5 to ≤10 cm; >10 to ≤15 cm; >15 cm. Determine the percentage.
- Tumor depth: Determine the percentage of tumors in the superficial
or deep (in large muscle mass, intra-abdominal, mediastinum, meninges...)
- Surgical resection margin: Determine the percentage of R0, R1, R2
according to AJCC


8
R0: Grossly and microscopically negative (tumor 1 mm from the
cutting area)

R1: Microscopically positive (tumor less than 1 mm from the cutting
area)
R2: Grossly positive
Negative cross-section is R0, positive cross-section is R1 and R2
- Histological grading: The histological grading of STSs according to
FNCLCC is based on necrosis, multiplication index and the grade of
differentiation of the tumor.
- Assessing Ki67:
+ The Ki-67 marker was determined by the proliferation index of the
nucleus, determined based on the percentage of tumor cell nuclei that
caught color, divided into 3 levels according to Hasegawa et al.: grade 1:
little positive ( <10%), grade 2: moderately positive (10-29%) and grade 3:
strongly positive (≥30%). Determine percentages by groups.
+ Histological classification based on Ki-67: applied on the basis of the
FNCLCC system, replacing the multiplier index with the Ki-67 index.
- Prognostic stratification of the risk of metastasis of solitary fibrous
tumours based on 4 factors (age, size, mitosis, and necrosis) divided into 3
groups of levels: low risk, medium risk, high risk . Calculate the percentage
of groups.
- EGIST prognosis: EGIST risk subgroup was applied according to the
National Institute of Health (NIH) classification and modified NIH criteria.
It changes based on two characteristics: tumor size and mitotic index.
2.3.2. Techniques and tools for collecting information
- Collect information about age, gender, tumor location, tumor size, disease
spread based on test request form (surgeon's), medical records, diagnostic
imaging.
- Collect specimens and/or paraffin blocks in the archives.
- Handling macroscopic specimens, performing histopathological (HE) and
IHC testing techniques.
- For difficult and rare cases, send samples for further consultation at K

hospital or in the US and do other IHC markers or molecular biology.
Table 2.2. Some general information about diagnostic techniques
Number of consultations in the US
Number of cases of molecular biology (FISH,
done in the US)
Number of IHC staining cases

126/363 (34.7%)
4/363 (1.1%)
292/363 (80.4%)


9
Number of cases without IHC staining (HE 71/363 (19.6%)
alone)
Total number of antibodies used
86
Minimum number of antibodies used/a case
1 (2 cases)
Maximum number of antibodies used/a case
19 (1 case)
Average number of antibodies used/case
5.19
Set of most used antibodies/a case
7 (47 cases)
Widely used antibodies
1. S100: 204
2. CD34: 162
3. Ki67: 147
4. Fatty sarcoma A: 129

5. Desmin: 126
6. EMA: 103
7. MDM2: 91
8. CK: 79
9. TLE1: 68
Total number of immunohistochemical slides
1879
2.4. Data processing
The obtained data and results were processed by computer, using the
statistical software SPSS 16.0. Analyze and present data according to the
topic's objectives.
- Qualitative variables: Calculated as a percentage (%).
- Normally distributed continuous variables: Analyze the relationship
between variables using χ2 test (in case the expected sample is less than 5,
the exact test method will be used (Exact Probability Test: Fisher and Phi
and Cramer's. ..) The difference is statistically significant when p < 0.05.
2.5. Errors and how to fix them
- Sampling error: only select cases that meet the required research
criteria to be included in the study.
- Error due to data mining: only taking the medical records with
enough information in the research form to study.
- Test error: Comply with the testing process of the Ministry of Health,
Viet Duc Hospital and the manufacturer's recommendations. There is
always a negative control and a positive control in each test run. 2
independent readers (student and instructor). In case of disagreement, the
results will be consulted with domestic and foreign doctors (Brigham and
Women's Hospital of Harvard University, USA).


10

2.6. Ethics in research
The study was conducted on patient tumor specimens, from
archival specimens and paraffin blocks, without performing procedures on
patients. The study was approved by the ethics committee in biomedical
research – Hanoi Medical University, certificate No. 219/HĐĐĐHYHN,
December 30, 2016.
CHAPTER 3
RESEARCH RESULTS
3.1. Some general results on age, gender, tumour position
3.2. Histopathological and immunohistochemical features.
3.2.1. Some common features
Table 3.3. Subgroups of soft tissue sarcomas by origin
Group of Soft tissue sarcoma origin
Quantity (n)
Ratio (%)
Adipocytic
97
26,7
Fibroblastic and myofibroblastic
106
29,2
So-called fobrohistiocytic
1
0,3
Smooth muscle
30
8,3
Skeletal muscle
22
6,1

Nerve sheath
17
4,7
Vascular
5
1,4
Chondro-osseous
1
0,3
EGIST
8
2,2
Perivascular
0
0
Uncertain differentiation
54
14,9
Undifferentiated/unclassified
22
6,1
363
100
Total
Comments: Fibroblastic and myofibroblastic sarcomas accounts for the
highest proportion with 29.2%, followed by liposarcoma with 26.7%,
sarcoma of uncertain differentiation group with 14.9%. The group of socalled fibrohistiocytic tumour and chondro-osseous tumour had 1 case
(accounting for 0.3%). There are no cases in the perivascular group.
3.2.2. Histopathological characteristics, immunohistochemistry of some
histopathological subtypes

● Liposarcoma:
- Histopathological type: Among the total 97 cases of liposarcoma, the
dedifferentiated type had the highest rate (50.5%), followed by the Welldifferentiated type (37.1%), the myxoid type (12.4%).


11
- Immunohistochemical features:
Table 3.5. Characterization of some IHC markers of liposarcoma
Marker
Type

Positive foci
N (rate)

Diffuse positivity
N (rate)

15 (34,9%)

21 (48,8%)

7 (16,3%)

43 (100%)

MDM2

4 (7%)

25 (43,9%)

28 (49,1%)

57 (100%)

CDK4

1 (2,5%)

14 (35%)

25 (62,5%)

40 (100%)

HMGA2

3 (7,1%)

8 (19,1%)

31 (73,8%)

42 (100%)

S100

Negative
N (ratio)

Total N
(ratio)

Comments: In the study, there was 1 case of dedifferentiated liposarcoma
with a focal point of differentiation with a rhabdomyoblast component
positive for Desmin and Myogenin, with a spindle cell component that was
positive for MDM2 and CDK4.
● Fibroblastic and myofibroblastic tumours
Table 3.6. Histopathological types of Fibroblastic and myofibroblastic
tumours
Histopathological type
Quantity (n)
Ratio (%)
DFSP
DFSP-FS
Malignant solitary fibrous tumor
Low grade fibroblastic sarcoma
Myxofibrosarcoma
Low grade fibromyxoid sarcoma
Malignant inflammatory
myofibroblastic tumor
Total

24
21
50
1
8
1
1

22,6
19,8
47,2
0,9
7,5
0,9
0,9

106

100

Table 3.7. The relationship between DFSP and DFSP-FS with CD34
Histopathological CD34 diffusely
type
positive
17 (89,5%)
DFSP

CD34 foci positive
or negative
2 (10,5%)

19 (100%)

Total

DFSP-FS

7 (43,7%)

9 (56,3%)

16 (100%)

Total

24 (68,6%)

11 (31,4%)

35 (100%)

p = 0,009


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Comments: In the DFSP group, the rate of CD34 positive or
negative was very low, only 10.5%; while in the DFSP-FS group, the rate
of CD34 positive or negative increased to 56.25%; statistically significant
relationship with p = 0.009.
Immunohistochemistry of solitary fibrous tumors:
- STAT6: 19 cases of solitary fibrous tumors were stained with
STAT6, 18/19 positive cases accounted for 94.7%.
- CD34:
Table 3.8. Relationship between solitary fibrous tumors site and CD34
Location of
CD34
CD34 foci

solitary
diffusely
positive or
Total
fibroids
positive
negative
7 (22,6%)
24 (77,4%)
31 (100%)
Meningitis
5 (62,5%)
3 (37,5%)
8 (100%)
Other
12
(30,8%)
27
(69,2%)
39(100%)
Total
P = 0,029
Comments: In malignant solitary fibrous tumours, the rate of CD34
positive or negative in meningeal sites (77.4%) is much higher than in other
sites than meninges (37.5%). The difference is statistically significant with
p=0.029.
● Rhabdomyosarcoma:
Histopathological type: in 22 cases of rhabdomyosarcoma, the most
common was the embryonal rhabdomyosarcoma (40.9% (9/22), followed
by the alveolar rhabdomyosarcoma 27.3% (6/22), the spindle cell

rhabdomyosarcoma 18.2% (4/22), polymorphic rhabdomyosarcoma 9.1%
(2/22), epithelioid rhabdomyosarcoma 4.5% (1/22).
Immunohistochemistry: Myogenin was positive in 17/19 cases (89.5%),
Myo-D1 was positive in 11/13 positive cases (84.6%), Desmin was positive
in 19/19 positive cases ( 100%).
● Malignant Peripheral Nerve sheath Tumor (MPNST):
Histopathology: In this study, we recorded 17 cases of MPNST, in which
3/17 cases of malignant Triton tumor (17.6%), 14/17 cases of normal type
MPNST (82.4%) (02 cases with differentiated osteosarcomatous
component), no cases with epithelioid type MPNST.
Immunohistochemistry: 3/3 cases of malignant Triton tumor were positive
for Desmin, Myogenin and Myo-D1 in regions with rhabdomyoblast; 5/5
cases of MPNST of normal type are negative for these 3 markers. Over 10
cases were stained with H3K27me3, 6/10 cases of complete loss of


13
expression accounted for 60%, 1/10 cases of loss of regional disclosure
accounted for 10%, 3/10 cases of no loss of disclosure accounted for 30%.
MPNST is positive for S100 (9/16 – 56.23%), SOX10 (3/10 – 30%).
● EGIST:
EGIST accounts for 2.2% (8/363) in all STS and 5.9% (8/136) in
retroperitoneal and intra-abdominal STS. 6/8 cases of simple spindle cell
EGIST accounted for 75%, 2/8 cases of mixed spindle cell and epithelioid
EGIST accounted for 25%, no cases of EGIST simple epithelium. IHC: 8/8
cases were diffusely positive for CD117 and DOG1.
● Sarcoma of uncertain differentiation:
Table 3.10. Classification of sarcomas of uncertain differentiation
Histopathological type
Quantity (n)

Ratio (%)
Synovial sarcoma
28
51,9
Epithelioid sarcoma
7
12,9
Alveolar soft part sarcoma
5
9,2
Clear cell sarcoma
3
5,6
Extraskeletal myxoid chondrosarcoma
3
5,6
Extraskeletal Ewing's sarcoma
3
5,6
Desmoplastic small round cell tumor
3
5,6
Extrarenal malignant pecoma
1
1,8
Extrarenal malignant teratoid tumor
1
1,8
Total
54

100
Synovial sarcoma: In 28 cases of synovial sarcoma, there were 15
cases of monophasic spindle cell type (53.6%), eight cases of biphasic type
(28.6%), and 05 cases of poorly differentiated type (17.8%). 14/28 cases
had collagen-rich stroma, 02 cases had calcifications between spindle cells.
IHC: TLE1 was positive in 23/23 cases (100%), of which was diffusely
positive 95.6% in histopathological types, 01 case was focally positive in
poorly differentiated type; EMA was positive in 16/24 cases (66.7%),
diffusely positive in 3/24 cases (12.5%); negative in 5/24 cases (20.8%);
CK was positive in 15/22 cases (68.2%), diffusely positive in 1/22 cases
(4.5%), negative in 6/22 cases (27.3%).
Alveolar soft part sarcoma: 05 patients have similar microscopic
appearance, with epithelial tumor cells, bright-colored or eosinophilic
cytoplasm, central nuclei, rare atypical nuclei and mitotic nuclei, arranged
arranged in a cavity, alveolar structure with a dense structure, interspersed
with a proliferative vascular system. IHC staining with TFE3 and both gave
positive results at levels 2+ to 3+. Other markers (CK, CD56,


14
ChrommograninA, S100, Synaptophysin, Myogenin, Desmin, RCC, Pax-8,
HMB45, MelanA, Hepa-1, ERG, TTF1, Inhibin, GFAP) were negative for
differential diagnosis. .
Epithelioid sarcoma (ES): 07 cases of ES in the study had similar
histopathological images, rhabdoid cells or epithelial cells, large nuclei,
clear nuclei, variable mitotic ratio (from 12 to 28), cytoplasm wide, some
acidophilic, cell boundaries unclear. The tumor has a central cord, cluster,
foci, and necrotic structure that produces a pseudo-granuloma image. IHC:
Ck was positive in 7/7 cases (100%); EMA is positive in 4/4 cases (100%);
CD34 positive drive 6/6 cases (100%); ERG was positive in 3/4 cases

(75%); 6/6 cases were negative for CD31; 7/7 cases of complete loss of
expression with INI1 marker (nuclear negative). 1/3 of cases (33.3%) had
p63 positive for the disease.
● Undifferentiated/unclassified sarcoma:
Table 3.11. Histopathological types of undifferentiated/unclassified
sarcomas
Quantity
Ratio
Histopathological type
(n)
(%)
Unclassified spindle cell sarcoma
8
36,4
Undifferentiated polymorphic sarcoma
7
31,9
Unclassified epithelial and spindle cell sarcomas
2
9,1
Undifferentiated epithelial cell sarcoma
1
4,5
Unclassified spindle cell and myxoid sarcoma
2
9,1
Undifferentiated round and spindle cell sarcoma
1
4,5
Myogenic-differentiated polymorphic sarcoma

1
4,5
Total
22
100
Immunohistochemistry: 22 IHC staining cases did not have specific
markers. They were negative for epithelial line markers (CK-, EMA-),
melanoma lineage markers (S100-, HMB45-, MelanA-).
3.3. Some macroscopic and microscopic factors have prognostic
significance
3.3.1. Some macroscopic factors
- Size of the tumor: the smallest is 1.5 cm; the largest 50 cm; on
average 11.3cm, ≤5cm has 88/363 cases (24.2%); >5-≤10cm has 120/263
cases (33.1%); >10- ≤15cm with 53/363 cases (14.6%); >15cm has 102/363
(28.1%).
- Tumor depth: 87/363 cases (24%) tumors are superficial
(subcutaneous); 276/363 cases (76%) deep tumors. In which in trunk,


15
extremities and head and neck, deep tumors accounted for 59.2% (126/213)
and superficial tumors accounted for 40.8% (87/213).
3.3.2. Surgical resection margin
The rate of R0 was 28.7% (104/363); R1-2 was 71.3% (259/363),
of which R1 was 50.6%.
3.3.3. Histological grade according to FNCLCC
- Over 355 cases of STS (except 08 cases of EGIST), histological
grade III accounted for the highest rate 46.5% (165/355), followed grade II
30.1% (107/255) and grade I was 23.4% (83/355).
Table 3.16. The relationship between histological grade according to

FNCLCC and R
Histological grade
R0
R1-2
Total
according to FNCLCC
40(48,2%)
43(51,8%)
83(100%)
Grade I
Grade II

29(27,1%)

78(72,9%)

107(100%)

Grade III

30(18,2%)

135(81,8%)

165(100%)

Total

99(27,9%)

256(72,1%)

355(100%)

p < 0,0001
Comments: The higher the histological grade according to FNCLCC
is, the higher the rate of R1-2 with p<0.0001 is.
3.3.4. Ki-67
Table 3.19. Relationship of histological grade according to Ki-67 with R
Histological grade
R0
R1-2
Total
according to Ki-67
12(50%)
12(50%)
24(100%)
Grade I
Grade II

15(24,6%)

46(75,4%)

61(100%)

Grade III

7(12,7%)

48(87,3%)

55(100%)

Total

34(24,3%)

106(75,7%)

140(100%)

p = 0,002
Comments: The higher the histological grade according to Ki-67 is, the
higher the percentage of R1-2 with p = 0.002 is.
3.3.5. Prognosis of some histopathological types
● DFSP and DFSP-FS
- With tumor size:


16
Table 3.20. Relationship between DFSP & DFSP-FS with tumor size
Tumor size
DFSP
DFSP-FS
Tổng
20 (71,4%)
8 (28,6%)
28 (100%)
≤ 5 cm

> 5 cm

4 (23,5%)

13 (76,5%)

17 (100%)

Total

24 (53,3%)

21 (46,7%)

45 (100%)

p = 0,002
Comments: The rate of DFSP-FS was 28.6% in the group of tumor
size ≤ 5 cm, increased to 76.5% in the group of tumor size > 5 cm, the
relationship was statistically significant with p = 0.002.
- R: The percentage of R1-2 cut area was 50% in DFSP, increased to 66.7%
in DFSP-FS, the relationship was not statistically significant with p = 0.366.
● Prognostic stratification of solitary fibrous tumours
Table 3.22. Risk stratification of solitary fibrous tumours
Risk stratification for
Quantity (n)
Ratio (%)
metastasis
Low risk (0-3 points)
28

56
Moderate risk (4-5 points)
17
34
High risk (6-7 points)
5
10
Total
50
100
Comments: Over 50 cases of malignancy alone, the low-risk group
accounted for the most 28 cases (56%), the high-risk group accounted for at
least 10%.
● Some prognostic factors for dedifferentiated liposarcoma
- Histological grade of dedifferentiated liposarcoma according to
FNCLCC: In 49 cases of dedifferentiated liposarcoma, there were 7 cases
of grade I (14,3%), 26 cases of grade II (53.1%), 16 cases of grade III (32.6%).
● Prognostic factors of EGIST
Table 3.25. EGIST risk classification by size and mitotic count
Tumor size
Number of
Risk group
Mitosis/5mm
(cm)
patients (ratio)
according to NIH
>5 to ≤10
≤5
1 (12,5%)
Intermediary

>5 to ≤10
>5
2 (25%)
High
>10
>5
5 (62,5%)
High
Comments: 1/8 cases belong to intermediate risk group (12.5%); 7/8 cases
belong to high risk group (87.5%).


17
CHAPTER 4
DISCUSSION
4.1. Regarding the histopathological and immunohistochemical
characteristics
Results from Table 3.3 in our study showed that sarcomas belonging
to the fibroblast/fibroblast group accounted for the highest percentage
(106/363; 29.2%); liposarcoma ranked second (97/363; 26.7%), followed
by group of uncertain origin (14.9%), leiomyosarcoma ranked 4th (8.3%),
followed by undifferentiated/unclassified sarcoma and rhabdomyosarcoma
(both 6.1%), MPNST (4.7%); 08 cases of EGIST (2.2%), 05 cases of
vascular origin (1.4%) and 01 case of osteochondrosis (0.3%). This result is
similar to some previous studies that tumors of fibroblast/fibroblast origin
and adipose origin are the most common. Research by Coindre (1994),
liposarcoma accounts for 13.7%, ranking second after malignant fibrous
histiocytoma. Research by Yusuf et al on 264 STS in general showed that
rhabdomyosarcoma was the most common (20.5%), followed by DFSP
(19.7%), liposarcoma ranked 3rd (12%). In general, there is a large

difference in the rate of histopathological subtypes between authors, both at
home and abroad. The difference in research results of the authors shows
the complexity, diversity in histopathology and the lack of consensus in
diagnostic criteria among pathologists. Tumors in different tumor locations
have different histopathological images, research by Nguyen Dai Binh and
Bui Thi My Hanh on peripheral soft tissue sarcoma, liposarcoma only ranks
6th because these two studies did not STS are in the abdominal cavity and
retroperitoneum where liposarcomas are most common. On the other hand,
the variation in the results of the studies by the authors is due to the studies
carried out in different times, using different classifications. Previous
studies also abused the term malignant fibrous histiocytoma in the diagnosis
of sarcomas of histiocytic and fibrous origin, after adjustment, the rate of
this histological type gradually decreased, to about 12 ,6% and 5%. The
2013 WHO classification does not exist for the term malignant fibrous
histiocytoma, tumors that resemble this type are classified as
undifferentiated polymorphic sarcoma. Moreover, the continuous
development of science and technology applied in medicine has brought a
deeper understanding of the pathology of STS, applied in diagnosis and


18
treatment, especially the New findings in cytogenetics (moderately positive)
and molecular shrinkage of unclassified/ undifferentiated tumors.
IHC not only plays a role in the differential diagnosis of STS from
benign pseudosarcoma or non-sarcoma malignancies (lymphoma, malignant
melanoma, poorly differentiated carcinoma), but is also valuable in
classifying sarcomas according to different origins. However, despite
making many IHC markers at home and abroad, in our study there were still
22 cases (6.1%) in the undifferentiated/unclassified group.
The development of science and technology, especially the positive

mean and molecular biology in cancer in general and STS in particular, has
helped to discover many new genes, help diagnose the disease, and at the
same time help to disease classification, prognosis and treatment. It is thanks to
the development of molecular biology that has helped give birth to new
classifications of the WHO 2013 and 2020. When new genes are discovered,
scientists also try to find and create IHC markers of equivalent molecular
significance to ease day-to-day diagnosis, replace expensive genetic tests,
this is the research trend of present and future. In this study, we initially
used some molecularly significant IHC markers, which were performed at
the surgery department of Viet Duc hospital or some pathology centers in
Vietnam. such as the Center for Pathology - Cytology at K hospital. IHC
with MDM2 and CDK4 markers is used in the definitive diagnosis of welldifferentiated and dedifferentiated liposarcoma and can be an alternative to
FISH. It is thanks to these markers that some cases were initially diagnosed
as pleomorphic liposarcoma, but when IHC staining showed that tumor
cells were positive for MDM2 or CDK4, it was re-diagnosed as
dedifferentiated liposarcoma. The rate of these markers in our study is
similar to other studies. The STAT6 marker has high sensitivity and
specificity in solitary fibrous tumours. INI1 was lost to expression in
epithelioid sarcoma (7/7 cases) and malignant extrarenal teratoid tumour
(1/1 case). MUC4 was positive for cytoplasm in low-grade fibromyxoid
sarcoma (1/1 cases). TFE3 is positive for tumor cell nuclei in alveolar soft
part sarcoma. TLE1 is positive in all types of synovial sarcoma. In addition,
a number of other new IHC markers made at the Anatomy Pathology
Center (USA) such as H3K27me3, ETV4, NKX2.2, BCOR, CCNB3...
These markers really helped for Diagnosis and identification of
histopathological type, thereby classifying the disease, helping to predict


19
and treat the disease. Molecular biology techniques (FISH) are also used in

some specific cases (difficult, rare cases) or immunohistochemistry shows
weak, atypical due to poor fixation. FISH technique is used to identify some
genes such as: DDIT3, MDM2, PGDFB, EWSR1. Although the number is
not much, the research is a premise for pathology departments in Vietnam
to develop more molecularly significant immunohistochemical markers,
deploy molecular biology techniques in the diagnosis of STS in particular
and cancer in general.
4.2. Regarding some macroscopic and microscopic factors with
prognostic significance
● Tumor size
The larger the tumor is, the more difficult it is to perform
conservative surgery and often have distant metastases when first
diagnosed. The results of this study showed that: tumors > 5cm (75.8%),
tumors >10 cm (42.7%). The study of Alexander S et al on 2084 primary
soft tissue sarcoma in adults also showed similar tumor size with 759 cases
(36.7%) tumor ≤ 5 cm, 631 cases (30.4%) tumor 5.1- 10 cm and 680 cases
(32.4%) with tumors > 10 cm; When considering the rate of R1 according
to the primary tumor size: ≤ 5 cm (13%); 5.1 - 10 cm (19%); 10.1 - 15 cm
(26%); 15.1 - 20 cm (37%); and > 20 cm (43%) (P < 0.001). From the
results of studying prognostic factors for soft tissue sarcoma in the trunk
and retroperitoneum, author Singer S and colleagues came to the conclusion
that tumors with large size > 5 cm (p = 0.018) are the important
independent prognostic factor for survival.
● Surgical resection margin
In order to avoid local recurrence and distant metastases, the surgical
resection must be "clean" i.e. free of tumor cells and at least 1 mm from
healthy tissue. Negative surgical resection after surgery had a low local
recurrence rate (9%) despite not receiving adjuvant radiotherapy. Positive
surgical resection is a poor prognostic factor for both recurrence and
survival. In this study, the rate of negative microscopic section was very

low 28.7% (104/363); the positive section rate is high 71.3% (259/363) (of
which the microscopic positive (R1) is 50.6% (184/363)). Studies analyzing
the prognostic factors of deep and retroperitoneal soft tissue sarcoma have
shown that a significant prognostic factor in metastatic survival is local
disease control. The 5-year metastasis-free survival was 73% for locally


20
controlled soft tissue sarcomas compared with 19% for locally recurrent
soft tissue sarcomas at 5 years (p=0.0013).
● Histological grade
Over time, many histological grading tables have been proposed, but
currently the FNCLCC is the most widely applied and has been
recommended by the WHO for use in clinical new type of STS. This system
is more precisely defined, clearer, and potentially more repeatable in the
practice of pathologists. Histological grading of STSs according to
FNCLCC is based on necrosis, mitotic index and tumor differentiation.
When grading histology according to FNCLCC on 355 STSs, our study
results showed that grade III is the most common (46.5%), followed by
grade II (30.1%) and low grade. especially grade I (23.4%). This result is
quite similar to the results of Bui Thi My Hanh (2010): Grade III STS is the
most common (43.1%), followed by grade II (39.4%) and the lowest is
grade II. I (17.5%) but it is much different from the study of Nguyen Dai
Binh (2003) who also ranks peripheral soft tissue sarcomas according to the
FNCLCC, grade I is the most common (44%) and the lowest is grade III
(15.7%). Studying the relationship between histological grade according to
FNCLCC and surgical resection on 355 patients (except GIST) found that
histology grade I has a positive rate of 51.8%, this rate is high in the grade I
group. Histological grade II was 72.9% and histology grade III was 81.8%.
Thus, the higher the histology, the higher the percentage of surgical

resection and the higher the tumor with p<0.001. Surgical resection margin
with tumor (R1-2) is a poor prognostic factor for the patient's ability to
survive metastasis-free and disease-free survival.
● Ki-67 marker in the prognosis of soft tissue sarcoma
MIB-1 histological grading is a new attempt based on the
overexpression of Ki-67 (MIB-1 system). Ki-67 expression was assessed on
a three-point scale (<10%, 10–29% and ≥30%). Applying on the basis of
the FNCLCC system, histological grades I - II - III will be totaled for three
parameters (tumor differentiation, necrosis and Ki-67 index). Evaluation of
histological grade according to Ki-67 in 140 patients, the rates of
histological grades I, II and III were 17.1%, 43.6% and 39.3%, respectively.
Many studies suggest that there is a significant correlation recorded
between the histological grade according to the conventional FNCLCC and
the histological grade according to the Ki-67 index. Therefore, IHC staining


21
with Ki-67 can be used to accurately classify the histology of STSs, thereby
helping in the management, monitoring and treatment of patients. The
results of Table 3.19 show that the rate of R1-2 surgical resection area in
the Ki-67 histological groups with grade I is 50%, increased to 75.4% in
grade II and 87.3 in grade III. %; The higher the Ki-67 histological grade,
the higher the percentage of surgical resection and the higher the tumor
with p = 0.002. For cases where it is difficult to evaluate the multiplier
index, especially on small biopsies, Ki-67 can be used to predict disease.
● Histological type
Histological type is one of the most important factors affecting the
treatment and prognosis of STS. Within a histological subtype, the subtypes
also have different prognostic significance: well-differentiated liposarcoma
and myxoid liposarcoma have a good prognosis, low recurrence rate, and

high survival in contrast to pleomorphic liposarcoma and dedifferentiated
liposarcoma. Many studies have demonstrated that histological type is a
prognostic factor for both relapse and survival and histological type
determines the adjuvant chemotherapy to increase survival time.
Prognosis of some common histopathological types:
- DFSP and DFSP-FS:
Dermatofibrosarcoma protuberans (DFSP) is a slow-growing
cutaneous tumor with very low metastatic potential but with significant
invasiveness and local destruction with a local recurrence rate of 0 up to 50%.
Location, surgical resection, presence of fibrosarcoma-like component (DFSPFS), loss of CD34 expression affect prognosis. DFSP-FS is generally
considered to be a more progressive variant than conventional DFSP. Recent
studies better define the differences between these tumors and determine the
prognostic significance in the presence of a fibrosarcoma-converting
component. Hoesly et al studied 188 cases, 171 (91%) DFSP and 17 (9%)
DFSP-FS. Relapse-free survival was significantly different between groups
over time (p = 0.002). The 1-year and 5-year recurrence-free survival rates
were 94% and 86%, respectively, for DFSP, compared with 86% and 42%
for DFSP-FS. There were no distant metastases in DFSP and 18% (3/17)
had distant metastases in DFSP-FS (p<0.001). There were no statistically
significant differences in age at diagnosis, sex, race, symptoms, maximum
tumor size, muscle/skeletal invasion or time of tumor appearance before
diagnosis. Over 45 cases of DFSP in our study, there were 21 cases with


22
fibrosarcoma component transformation (DFSP-FS), accounting for 46.7%.
This rate is higher than many previous studies, only 10-20%. The
explanation for this difference may be due to the fact that Viet Duc Hospital
is a last-line surgical hospital, the disease is at a late stage when the tumor
is large in size or recurs many times.

- Stratification of prognostic factors of solitary fibrous tumours:
The 3-level model established by Demicco et al combines age (< 55
or 55), tumor size (< 5 to ≥ 15 cm in increments of 5 cm) and mitotic count
(0.1 - 3, or ≥4/10HPF). This model was applied in 79 cases of solitary
fibrous tumours; The addition of necrosis as the fourth endpoint (<10% or
≥10%) increased the accuracy of the low-risk and high-risk groups for
metastasis. Our study included 50 cases of malignant solitary fibrous
tumors (according to the 2013 WHO classification with the standard of ≥ 4
divided/10 HPF). Scoring according to the metastasis risk scorecard based
on 04 criteria of Demicco EG et al. showed that the low risk group
accounted for a high percentage (56%), the group at moderate risk of
metastasis (34%), the group at risk high muscle (10%). This result is quite
similar to the study of Demicco EG et al., on 79 cases of solitary fibrous
tumour extra meningiomas, there were 45 cases of low risk group (57%),
average risk of 23 cases cases (29%), high risk 11 cases (14%). Although
malignant solitary fibrous tumour is often meningeal, it causes early clinical
presentation (associated with increased intracranial pressure) so early
hospitalization leads to a lower age of detection (usually < 55 years). age),
when the tumor size is small.
- Prognosis of dedifferentiated liposarcoma:
In our study, dedifferentiated liposarcoma was found mainly in the
retroperitoneal - intra-abdominal location accounted for 93.9%, the site was
considered to have a poor prognosis, the trunk position had 03 cases,
accounting for cases 6.1% (in which 01 case in the chest wall and 02 cases
in the groin - scrotum), no tumors in other locations such as mediastinum
and extremities. Dedifferentiated liposarcoma in the retroperitoneal - intraabdominal position, in addition to its large size (87.8% of cases > 10cm)
also has the ability to invade viscera such as stomach - intestines, spleen,
tail, pancreas, kidney – ureters, bladder, uterus – ovaries, large blood
vessels… make surgery difficult. The WHO 2020 classification has updated
and recommends the use of the FNCLCC system for histological grading of