PATHOLOGY OF VASCULAR SKIN LESIONS - PART 1 pptx

PATHOLOGY OF
VASCULAR SKIN LESIONS
CLINICOPATHOLOGIC CORRELATIONS
Omar P. Sangüeza, MD
Luis Requena, MD
HUMANA PRESS
CD-ROM
Included
P
ATHOLOGY

OF
V
ASCULAR
S
KIN
L
ESIONS
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CURRENT CLINICAL PATHOLOGY
IVAN DAMJANOV, MD
SERIES EDITOR
Pathology of Vascular Skin Lesions: Clinicopathologic Correlations, by Omar
P. Sangüeza,
MD, and Luis Requena, MD, 2003
Practical Immunopathology of the Skin, by Bruce R. Smoller,
MD, 2002
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PATHOLOGY OF
VASCULAR SKIN LESIONS
C

LINICOPATHOLOGIC
C
ORRELATIONS
HUMANA PRESS
TOTOWA, NEW JERSEY
OMAR P. S ANGÜEZA, MD
Departments of Pathology and Dermatology
Wake Forest University School of Medicine
Winston-Salem, NC
LUIS REQUENA, MD
Department of Dermatology
Fundación Jiménez Díaz
Universidad Autonoma
Madrid, Spain
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© 2003 Humana Press Inc.
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the contents in this publication.
Cover design by Patricia F. Cleary.
Cover illustration: Histopathologic features in plaque lesions of Kaposi’s sarcoma: The “promontory” sign evident
around preexisting capillaries. (See Fig. 9C in Chapter 9 and companion CD-ROM and discussion on pp. 223–224.)
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Library of Congress Cataloging-in-Publication Data
Sangüeza, Omar P.
Pathology of vascular skin lesions : clinicopathologic correlations / Omar P. Sangüeza, Luis Requena.
p. ; cm. (Current clinical pathology)
Includes bibliographical references and index.
ISBN 1-58829-182-0; 1-59259-360-7 (e-book)
1. Skin Blood vessels Tumors. 2. Skin Blood-vessels Pathophysiology. I. Requena, Luis. II. Title. III.
Series.
[DNLM: 1. Skin Neoplasms pathology. 2. Skin Diseases, Vascular pathology. WR 500 S226p 2003]
RC280.S5 S264 2003

616.99'27707 dc21
2002027332
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To Catherine, Edith, and Charles,
my beloved family.
Without their love, support, and patience
neither this book nor any other enterprise
would have been possible.
To Koki,
in appreciation of her love and limitless patience.
Without her, nothing makes sense.
Sangueza_FM_Final 01/30/2003, 1:29 PM5
Sangueza_FM_Final 01/30/2003, 1:29 PM6
Why a book on cutaneous vascular proliferations? There are several compelling
reasons to justify the existence of a book on this topic. One of the most important is that
cutaneous vascular proliferations are exceedingly common and affect a large number of
individuals of both sexes and within a wide age range. They make up a broad spectrum
of lesions with morphological and biological variations, ranging from hamartomas to
highly malignant, aggressive neoplasms. Although the diagnosis of some vascular lesions
is straightforward, many entities pose significant problems in diagnosis, classification,
and treatment. Within the past two decades there has been an increase in the number of
patients affected with Kaposi’s sarcoma, related to the epidemic of the acquired
immunodeficiency syndrome (AIDS). As a consequence, a number of variants and
vascular lesions that simulate Kaposi’s sarcoma, both clinically and histopathologically,
have been described. In addition, other vascular entities not related to Kaposi’s sarcoma
have been introduced in the literature. All of these have added confusion to an already
complicated field. Since there are no recent textbooks on this subject, we felt an update
was overdue.
The aim of Pathology of Vascular Skin Lesions: Clinicopathologic Correlations is to
provide a comprehensive and in-depth review of all vascular proliferations involving the

skin and subcutaneous tissue, including recently described entities. Although our work
is primarily directed to pathologists, dermatologists, and dermatopathologists, its wide
scope will make it useful to pediatricians and plastic surgeons as well.
Pathology of Vascular Skin Lesions: Clinicopathologic Correlations is divided into
three parts. The first part covers classification and nomenclature of vascular neoplasms,
an area that is still controversial. We propose a new classification with the hope that it
will bring more order into a chaotic arena. We recognize that this classification may have
some pitfalls and limitations, but we also believe that it is the most logical way to
approach the study of vascular proliferations.
In order to know what is abnormal, a student of the field should first know what is
normal, which is the reason for including a chapter on normal embryology, histology,
and anatomy of the skin vasculature. Another chapter is devoted to the use of special
techniques for the study of vascular proliferations.
In the second part, we include benign proliferations ranging from hamartomas and
malformations to benign neoplasms. The final part of the book deals with malignant
vascular proliferations, ranging from Kaposi’s sarcoma to angiosarcomas. It includes
some new entities, too.
The whole of Pathology of Vascular Skin Lesions: Clinicopathologic Correlations
was conceived in terms of a clinicopathologic correlation. The clinical and morphologic
vii
PREFACE
Sangueza_FM_Final 01/30/2003, 1:29 PM7
aspects of each entity are described in detail, including their differential diagnosis,
prognosis, and therapy. Each chapter is fully illustrated with both clinical and
histopathologic photographs, and we include color versions of all illustrations on the
accompanying CD-ROM. Additionally, there is a complete and updated list of references
for each particular section. We hope that you find this book interesting and useful.
This book was sponsored in part by Pathologists Diagnostic Services, PLLC, in
Winston-Salem, NC.
Omar P. Sangüeza, MD

Luis Requena, MD
viii Preface
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ACKNOWLEDGMENTS
Many colleagues contributed clinical pictures, histopathologic slides, or other
material for this review. We are very grateful to the following clinicians and
pathologists:
A. Bernard Ackerman,
MD (USA)
Antonio Aguilar,
MD (Spain)
Adolfo Aliaga,
MD (Spain)
Isabel Febrer,
MD (Spain)
M. Alba Greco,
MD (USA)
Gerardo Jaqueti,
MD (Spain)
Esperanza Jordá,
MD (Spain)
Helmut Kerl,
MD (Austria)
Heinz Kutzner,
MD (Germany)
Pablo Lázaro,
MD (Spain)
Beatriz López,
MD (Spain)
José M. Mascaró,

MD (Spain)
Thomas Mentzel,
MD (Germany)
Special thanks to: Di Lu,
MD (USA), who spent countless hours shooting micro-
photographs; Rita O. Pichardo,
MD (Venezuela), who helped to compile and organize all
photographic and written material, and to Steven Vogel,
MD, who corrected the manu-
script, offered support, and provided advice.
Figures 10 and 19 in Chapter 6, Figure 13 in Chapter 7, Figure 15 in Chapter 8, Figure
3 in Chapter 11, and Figure 35 in Chapter 8 have been previously published (J Am Acad
Dermatol 1977;37:523-49. J Am Acad Dermatol 1997;37:887-20. J Am Acad Dermatol
1998;38:143-75). These figures are reproduced here with permission of Mosby Inc.
Paula E. North,
MD (USA)
Celia Requena,
MD (Spain)
Jorge L. Sánchez,
MD (Puerto Rico)
Evaristo Sánchez Yus,
MD (Spain)
Pastor Sangüeza,
MD (Bolivia)
Andrés Sanz,
MD (Spain)
Jaime Tschen,
MD (USA)
Antonio Torrelo,
MD (Spain)

Sara O. Vargas,
MD (USA)
Antonio Vélez,
MD (Spain)
Angel Vera,
MD (Spain)
Michel Wassef,
MD (France).
ix
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Preface vii
Acknowledgments ix
Companion CD-ROM Inside Back Cover
1Embryology, Anatomy, and Histology
of the Vasculature of the Skin 1
1. Embryologic Aspects 1
2. Anatomic and Histologic Aspects of the Dermis and Blood Vessels 2
2 Special Techniques for the Study of Vessels
and Vascular Proliferations 7
1. Immunohistochemical Stains 7
2. Molecular Techniques 10
3. Cytogenetic Studies 12
3Classification of Cutaneous Vascular Proliferations 15
4Cutaneous Vascular Hamartomas 19
1. Phakomatosis Pigmentovascularis 19
2. Eccrine Angiomatous Hamartoma 23
5Cutaneous Vascular Malformations 27
1. Nevus Anemicus 29
2. Cutis Marmorata Telangiectatica Congenita 32

3. Nevus Flammeus 37
4. Hyperkeratotic Vascular Stains 47
5. Venous Malformations 51
6. Superficial Cutaneous Lymphatic Malformations 63
7. Cystic Lymphatic Malformations (Cystic Hygromas) 67
8. Lymphangiomatosis 70
6Cutaneous Lesions Characterized by Dilation
of Preexisting Vessels 73
1. Spider Angioma (Nevus Araneus) 73
2. Capillary Aneurysm-Venous Lake 76
3. Telangiectases 79
4. Angiokeratomas 86
5. Lymphangiectases 95
CONTENTS
xi
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7Cutaneous Vascular Hyperplasias 99
1. Angiolymphoid Hyperplasia with Eosinophilia 99
2. Pyogenic Granuloma 105
3. Bacillary Angiomatosis 112
4. Verruga Peruana 116
5. Intravascular Papillary Endothelial Hyperplasia
(Masson’s Pseudo-Angiosarcoma) 119
6. Pseudo-Kaposi’s Sarcoma 123
7. Reactive Angioendotheliomatosis 128
8 Benign Neoplasms 133
1. Angioma Serpiginosum 133
2. Infantile Hemangiomas 136
3. Cherry Angiomas (Senile Angiomas) 151
4. Arteriovenous Hemangioma 154

5. Hobnail Hemangioma (Targetoid Hemosiderotic Hemangioma) 157
6. Microvenular Hemangioma 161
7. Tufted Angioma 164
8. Glomeruloid Hemangioma 169
9. Acquired Elastotic Hemangioma 174
10. Kaposiform Hemangioendothelioma 177
11. Sinusoidal Hemangioma 182
12. Giant Cell Angioblastoma 184
13. Spindle Cell Hemangioma (Formerly Spindle Cell
Hemangioendothelioma) 186
14. Benign Lymphangioendothelioma 191
15. Benign Vascular Proliferations in Irradiated Skin 195
16. Glomus Tumors 198
17. Hemangiopericytoma 208
18. Cutaneous Myofibroma 212
9Malignant Neoplasms 217
1. Kaposi’s Sarcoma 217
2. Epithelioid Hemangioendothelioma 236
3. Endovascular Papillary Angioendothelioma (Dabska’s Tumor
or Papillary Intralymphatic Angioendothelioma) 241
4. Retiform Hemangioendothelioma 245
5. Composite Hemangioendothelioma 250
6. Cutaneous Angiosarcoma of the Face and Scalp of Elderly Patients
(Wilson Jones’ Angiosarcoma) 251
7. Cutaneous Angiosarcoma Associated with Lymphedema 258
8. Radiation-Induced Cutaneous Angiosarcoma 262
9. Epithelioid Angiosarcoma 268
10. Malignant Glomus Tumor (Glomangiosarcoma) 271
xii Contents
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10 Other Cutaneous Neoplasms
With a Significant Vascular Component 275
1. Multinucleate Cell Angiohistiocytoma 275
2. Angiofibroma 279
3. Angioleiomyoma 284
4. Angiolipoma 287
5. Cutaneous Angiolipoleiomyoma 290
6. Cutaneous Angiomyxoma 293
7. Aggressive Angiomyxoma 296
11 Disorders Erroneously Considered
as Vascular Neoplasms 299
1. Kimura’s Disease 299
2. “Malignant” Angioendotheliomatosis
(Intravascular Lymphomatosis) 304
3. Acral Pseudolymphomatous Angiokeratoma
in Children (APACHE) 309
Index 311
Contents xiii
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Chapter 1 / Vasculature of the Skin 1
1
1
Embryology, Anatomy, and Histology
of the Vasculature of the Skin
CONTENTS
EMBRYOLOGIC ASPECTS
ANATOMIC AND HISTOLOGIC ASPECTS OF THE DERMIS
AND BLOOD VESSELS
The skin is a complex organ responsible for numerous physiologic and immunologic

functions. It is conceptually the largest organ of the body (1). It weighs between 3 and
4 kg, constitutes 6% of body weight, and, on the average adult, covers an area of approxi-
mately 2 m
2
. The functions of the skin are numerous and diverse. Notably, it serves as a
barrier that excludes harmful chemicals and pathogens while retaining water and endog-
enous proteins. The skin also modulates body temperature, acts as a sensory organ,
protects against physical injury, is a component of the immune system, and has psycho-
social and aesthetic importance. It is composed of three principal layers: the epidermis,
the dermis, and the subcutaneous tissue. It also houses the adnexa, melanocytes, Langer-
hans cells and Merkel cells.
1. EMBRYOLOGIC ASPECTS
All components of the skin are derived embryologically from either the ectoderm or
the mesoderm. The ectoderm gives origin to the epidermis and the epithelial dermal
constituents, whereas the mesenchymal components of the dermis are derived from the
mesoderm.
The earliest evidence of skin is seen at the end of the first month of embryonic life, at
which time a single layer of cuboidal epithelium encases the embryo (2). By the fourth
to sixth weeks of gestation, this epithelium has evolved into a two-cell layered structure.
The outer layer, or periderm, is composed of glycogen-laden cells, superimposed upon
cuboidal cells that form the inner or basal layer (2). The periderm is in immediate contact
with the amniotic fluid, into which these cells are gradually shed to the point of total
disappearance by the 21st week of estimated gestational age (EGA). An intermediate
layer develops between the periderm and basal layer by the 11th week. At this point, the
inner layer evolves into the stratum germinativum, which continues to proliferate and to
serve as the source of epidermal cells throughout life. By the 21st week of EGA, the
intermediate layer has differentiated into the stratum spinosum, granulosum, and cor-
neum. The first semblance of cornification is seen after the fifth gestational month.
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2 Sangüeza and Requena / Pathology of Vascular Skin Lesions

Thereafter, there is increased production of keratohyalin granules, and the epidermal
cells near the surface lose their nuclei. Complete cornification is normally accomplished
by the sixth month of EGA.
The dermo-epidermal junction develops during the first trimester, and all the elements
of this layer are recognizable thereafter (3). The components of the basal layer are pro-
duced by the basal cells of the epidermis. During the first 3 months of intrauterine life,
cells migrate from the neural crest to the epidermis, where they become melanoblasts and
presumptively also Merkel cells. Merkel discs are recognizable by the 7th month, whereas
melanocytes can be identified with special stains by the 10th or 11th week (4). Langer-
hans cells are derived from the bone marrow to serve as immunomodulators. At entry into
the epidermis by the seventh week, they differ from mature Langerhans cells since they
express different antigens (5). Human leukocyte antigen-DR, as well as the CD1 antigen,
normal constituents of mature Langerhans cells, can be recognized by the 12th week of
EGA, whereas Birbeck granules can be identified ultrastructurally 2 weeks earlier (3).
Folliculo-sebaceous-apocrine units appear around the ninth week, initially in the head
and neck, notably in areas of the future eyebrows, eyelids, upper lip, and chin. They
develop in a cephalocaudal direction, and by the fourth month hair follicles are also
evident in the abdominal skin and elsewhere. Most of the hair follicles are present by the
fifth month, and probably no new hair follicle formation takes place after birth (2).
Sebaceous glands remain appended to hair follicles in extrauterine life, but most apocrine
glands involute shortly after birth and remain present only in select cutaneous areas,
notably the axillae, genital area, and mammary areola.
Eccrine glands appear on the palms and soles by the 12th week of EGA. They originate
as small proliferations of the basal layer, as protusions into the dermis and epidermis. In
the dermis they form unbranched, highly coiled glands whereas in the epidermis they
form the acrosyringium. Centrally positioned cells in these proliferations degenerate to
create the lumen of the gland; the peripheral cells differentiate into an inner layer of
secretory cells and an outer layer of myoepithelial cells.
During the first 5–7 weeks of intrauterine life, the dermis is mostly cellular. During this
early interval, there is no sharp demarcation between the dermis and the subcutaneous fat,

and there are no recognizable adnexal structures within the connective tissue. Between
the 8th and 9th weeks, the amount of collagen increases markedly in the extracellular
matrix, so consequently by the 10th–12th weeks the cellular dermis has been transformed
into a predominantly fibrous dermis. During this interval, the deep boundary of the
dermis is defined by a plexus of blood vessels and nerves that lie in a plane between
the dermis and subcutaneous fat. Once the dermis has become predominantly fibrous, as
it does by approximately the 13th week of EGA, vessels and nerves are recognizable, at
all levels of the dermis, unsheathed by connective tissue. Definite papillary and reticular
dermis is distinguishable by the 14th week (6) . Nerve endings are recognizable during
the fourth gestational week and continue to increase in number thereafter until the seventh
month of intrauterine life (7).
2. ANATOMIC AND HISTOLOGIC ASPECTS
OF THE DERMIS AND BLOOD VESSELS
The dermis, composed of, collagen, elastic fibers, and ground substance, harbors the
blood vessels and nerves. The blood supply of the dermis flows from a plexus, located
in the deep reticular dermis (Fig. 1). This conduit is connected with three more superficial
01/Sangüeza/1-6/F 01/14/2003, 10:32 AM2
Chapter 1 / Vasculature of the Skin 3
Fig. 1. Drawing of the normal vascularization of the skin. The blood supply of the dermis flows
from a plexus, located in the deep reticular dermis. This conduit is connected with three more
superficial plexuses, namely, the subpapillary plexus and the paired plexuses around the hair
follicles and eccrine glands. From the latter, progressively smaller arterioles ascend into the
dermis to branch finally into the numerous capillaries that richly supply the adventitial dermis. The
capillary loops that nourish each subepidermal papilla originate from the subpapillary plexus,
each loop consisting of an ascendant arterial limb and a descendent venous appendage. The venous
limb drains blood into progressively larger venules, which terminally empty into small veins of
the subcutaneous plexus.
plexuses, namely, the subpapillary plexus and the paired plexuses around the hair fol-
licles and eccrine glands (8–12). From the latter, progressively smaller arterioles ascend
into the dermis to branch into numerous capillaries that richly supply the adventitial

dermis. The capillary loops that nourish each subepidermal papilla originate from the
subpapillary plexus, each loop consisting of an ascendant arterial limb and a descendant
venous appendage. The venous limb drains blood into progressively larger venules,
which terminally empty into small veins of the subcutaneous plexus.
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4 Sangüeza and Requena / Pathology of Vascular Skin Lesions
Fig. 2. (A) Artery and vein within the subcutaneous tissue. The artery has a round to oval
structure with thick walls; the vein is elongated and the walls are thinner. (B) Higher magnification
of an artery showing thick muscular walls. (C) A Verhoeffs elastic stain to demonstrate the
prominent lamina elastica of the artery. (D) Vein showing thinner walls and an irregular lumen.
(E) Verhoeffs elastic stain showing elastic fibers within the wall; note that the fibers do not form
a distinctive structure.
The small arteries of the subcutaneous plexus and the arterioles of the dermis possess
three layers: the intima, the media, and the adventitia (Fig. 2). The intima is composed
Fig. 2
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Chapter 1 / Vasculature of the Skin 5
of endothelial cells and an internal elastica lamina. The media is formed predominantly
of smooth muscle cells, bounded by an external elastica lamina and adventitia that is
composed of fibroblasts with type III collagen and elastic fibers. The arterioles of the
ascending segment of the capillary loop inwardly possess endothelial cells and outwardly
are covered by pericytes, both constituents being surrounded by a basement membrane.
The smaller arterioles in the papillary dermis possess a single, continuous layer of endot-
helial cells, surrounded by a discontinuous layer of elastic fibers and smooth muscle cells.
The arteriolar capillaries are lined by a single layer of endothelial cells, surrounded by
an incomplete layer of pericytes.
Ultrastructurally, there is evidence that the endothelial cells are interconnected. The
passage of small molecules and exchange of fluids occur through pinocytosis. Small
vesicles formed at the surface of the endothelial cells, transported across the cytoplasm,
and released at the contraluminal membrane imbibe molecular elements. Postcapillary

venules possess endothelial cells, pericytes, and basal lamina surrounded by thin zones
of type III collagen. Venular capillaries are fenestrated, allowing the passage of large
molecules. The capillary veins that are part of the descending loop are composed of
endothelial cells, plentiful pericytes, and a multilayered basement membrane. The larger
venules are endowed with variable amounts of smooth muscle and elastic fibers but no
elastic membrane. Veil cells, unlike pericytes, have the appearance of flattened fibro-
blasts, and lie completely outside the vascular walls of all arterioles, capillaries, and
venules in the dermis. The veil cell demarcates the vessels from the surrounding dermis
and can be considered an adventitial cell (12).
Ultrastructurally, the endothelial cells have a well-developed endoplasmic reticulum;
their cytoplasmic compartment contains bundles of filaments with diameters of 5–10 µm
and pinocytotic vesicles that measure 50–70 nm across. Distinctively these cells contain
Weibel-Palade bodies. These are electron dense, rod-shaped cytoplasmic structures mea-
suring 0.1 × 3 µm. Intrinsically the Weibel-Palade body contains numerous small tubules
that measure 15 nm in thickness, as they mark the long axis of the body.
In certain regions of the body, notably the central face, the ears, and the pads and nail
beds of the fingers and toes, there are special vascular structures known as glomus bodies
that modulate blood flow and temperature. These are arteriovenous shunts, in which there
are direct connections between arterioles and venules, without interposition of capil-
laries. The arterial segment, or Suquet-Hoyer canal, has a narrow lumen and a wall of
20–40 µm thick (5). A single layer of lining endothelium is surrounded by a basement
membrane. Four to six layers of glomus cells form the media and an adventitia composed
of loose connective tissue. Glomus cells have an abundant, clear cytoplasm and round to
oval nuclei. Ultrastructurally, these cells have been considered to show smooth muscle
differentiation as evidenced by cytoplasm filled with myofilaments. The venous segment
of the glomus has a wide lumen with attenuated walls.
The lymphatic channels of the skin form a complex network that adheres to the dis-
tribution of arterioles and venules. The lymphatics serve in the control of the microcir-
culation; they line interstitial spaces and provide portals through which macromolecules
escape for drainage (13). Even the smallest lymphatic capillaries are relatively large,

often flattened tubes lined by an extremely attenuated single layer of endothelium and
surrounded by an indistinct and discontinuous basement membrane. They are not
endowed with pericytes. In contrast to the endothelial cells of the blood vessels, they
contain very few organ-specific characteristics. There are no fenestrae and only a few
01/Sangüeza/1-6/F 01/14/2003, 10:32 AM5
6 Sangüeza and Requena / Pathology of Vascular Skin Lesions
Weibel-Palade bodies. The lymphatics form small plexuses in the upper reticular dermis,
just below the subpapillary plexus of venules. There are no lymphatic structures within
the papillary dermis, except as a response to inflammation or the presence of raised
hydrostatic pressure. Occasional blind loops may extend upward into the base of the
papilla, but their numbers are few, even in the papillary foot. The superficial lymphatic
network drains into the collecting lymphatics; this retains the features of capillaries with
attenuated endothelial cells and absence of smooth muscle. The postcapillary lymph
vessels at the border between the dermis and subcutaneous tissue have wider lumina and
thicker connective tissue walls, few smooth muscles cells, and occasional valves. These
attributes serve to distinguish them from small blood vessels.
References
1. Goldsmith LA. My organ is bigger than your organ. Arch Dermatol 1990;126:301–2.
2. Larsen WJ. Development of integumentary system. In: Human Embryology. New York, Churchill
Livingstone, 1993:419–33.
3. Urmacher C. Normal skin. In: Histology for Pathologists. Sternberg SS, ed. New York, Raven Press,
1992:382–97.
4. Holbrook K, Underwood RA, Vogel AM, et al. The appearance, density and distribution of melanocytes
in human embryonic and fetal skin revealed by the anti–melanoma monoclonal antibody, HMB-45. Anat
Embryol 1989;180:443.
5. Jakubovic HR, Ackerman AB. Structure and function of skin: development, embryology, and physiology.
In: Dermatology, 3rd ed. Moschella SL, Hurley HR, eds. Philadelphia, WB Saunders, Co., 1992:3–87.
6. Johnsson CL, Holbrook KA. Development of human embryonic and fetal dermal vasculature. J Invest
Dermatol 1989;93:10S–17S.
7. Arthur RP, Shelley WB. The innervation of human epidermis. J Invest Dermatol 1959;32:397–411.

8. Yen A, Braveman IM. Ultrastructure of the human dermal microcirculation. The horizontal plexus of
the papillary dermis. J Invest Dermatol 1976;66:131–42.
9. Braveman IM, Yen A. Ultrastructure of the human dermal microcirculation. II. The capillary loops of
the dermal papillae. J Invest Dermatol 1977;68:44–52.
10. Braveman IM, Yen KA. Ultrastructure of the human dermal microcirculation. III. The vessels in the mid
and lower dermis and subcutaneous fat. J Invest Dermatol 1981;77:197–204.
11. Braveman IM, Yen KA. Ultrastructure of the human dermal microcirculation. IV. Valve containing
collecting veins at the dermal-subcutaneous junction. J Invest Dermatol 1983;81:438–42.
12. Braveman IM. Ultrastructure and organization of the cutaneous microcirculation in normal and patho-
logic states. J Invest Dermatol 1989;93:2S–9S.
13. Braveman IM, Sibley J, Yen KA. A study of the veil cells around normal, diabetic and aged cutaneous
microvessels. J Invest Dermatol 1986;86:57–62.
14. Terence RJ. Structure and function of lymphatics. J Invest Dermatol 1989;93:18S–24S.
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Chapter 2 / Special Techniques 7
7
2
Special Techniques for the Study
of Vessels and Vascular Proliferations
CONTENTS
IMMUNOHISTOCHEMICAL STAINS
MOLECULAR TECHNIQUES
CYTOGENETIC STUDIES
The recognition of vascular lesions is most often straightforward; however, sometimes
the use of additional techniques becomes necessary to secure a more definitive diagnosis,
notably when the vascular nature of a neoplasm mimics another category of neoplasm.
For example, epithelioid hemangioendotheliomas and epithelioid angiosarcomas may
simulate poorly differentiated carcinomas, even to the extent of positivity for the conven-
tional epithelial marker, cytokeratin (1,2). In still other cases the vascular nature of a
neoplasm may be obscured by a prominent inflammatory infiltrate (3,4). Special tech-

niques can help clarify the true nature of these problematic neoplasms.
Before the era of immunohistochemical techniques, much reliance was placed on
histochemical stains. Stains for reticulin and elastic fibers were the gold standard to detect
the presence of vascular differentiation. Enzymatic stains were less often employed.
Most of these techniques are currently outdated and seldom used. This chapter discusses
the evaluation and application of the common markers currently used for the detection
of vascular neoplasms. Molecular techniques receive less attention.
1. IMMUNOHISTOCHEMICAL STAINS
The most common markers used to assert the vascular nature of a lesion are von
Willebrand factor (vWF; formerly factor VIII-related antigen), CD34 (human hemato-
poietic progenitor cell antigen), CD31 (platelet endothelial cell adhesion molecule-1),
and Ulex europaeus lectin. More recently, vascular endothelial growth factor receptor-3
(VEGFR-3) and GLUT1 have been added to the armamentarium of immunohistochemi-
cal stains for the characterization of vascular lesions.
vWF was one of the first immunohistochemical markers to be developed, and it has
been utilized now for more than 15 years (5). The factor is an intrinsic secretory compo-
nent of endothelial cells. It has limited sensitivity but is present in most types of nonneo-
plastic endothelium, as well as in serum and body fluids. Although it is a good marker for
epithelioid hemangioendotheliomas, it is absent in most angiosarcomas. Being wide-
spread in distribution, it is usually present in areas of hemorrhage, exudation, and necro-
sis and thus can create heavy background staining that compromises interpretation (6).
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8 Sangüeza and Requena / Pathology of Vascular Skin Lesions
The Ulex europaeus lectin selectively binds a terminal fucosil residue of the H blood
group antigen to a unique endothelial glycoprotein. Although this marker generated
initial optimism because of its great sensitivity, it was subsequently discovered that the
targeted sugar is also present in normal epithelium, as well as in a wide range of epithelial
tumors (7).
CD34 (human hematopoietic progenitor cell antigen) is a 105–120-kDa transmem-
brane glycoprotein normally present in human hematopoietic progenitor cells (8). It was

initially developed for the characterization of acute leukemias, in which the expression
of this antigen is usually correlated with a poor prognosis. It was subsequently found to
also be present in endothelial cells, although those of lymphatic vessels express this
antibody in a less uniform fashion (9). The most commonly used monoclonal antibodies
to CD34 are My10 and QB-END 10, two reagents with comparable reactivities (6,10).
It has been validated that CD34 will intensely label mature, well-formed vessels but can
be nonreactive or weakly so with immature or poorly formed vessels. Thus, CD34 can
be nonreactive in granulation tissue, papillary intravascular endothelial hyperplasia, and
bacillary angiomatosis (11). On the other hand, it appears to be a dependable marker for
Kaposi’s sarcoma and angiosarcomas (6,12,13). A shortcoming of CD34 is its affinity for
other tissues of mesenchymal origin; thus, it stains fibrocytes, fat and perivascular cells.
Consequently, many neoplasms including dermatofibrosarcoma protuberans, solitary
fibrous tumor, epithelioid sarcomas and gastrointestinal stromal tumors are positive for
CD34 (14–17).
CD31 is a 130-kDa glycoprotein that mediates platelet cell adhesion to endothelial
cells (PECAM1). As one of the cell adhesion molecules, it belongs to the immunoglobu-
lin gene superfamily. Although normally present in endothelial cells, it is also a constitu-
ent of platelets, monocytes/macrophages, and subsets of lymphocytes, plasma cells, and
hematopoietic stem cells (6). The two monoclonal antibodies most commonly utilized for
detection of CD31 are JC/70A and EN4 (18,19). CD31, the most sensitive and specific
endothelial marker, is consistently present in angiosarcomas, hemangioendotheliomas,
Kaposi’s sarcomas, and hemangiomas (13). Among the nonvascular tumors, an occa-
sional carcinoma or epithelioid sarcoma may show weak staining with this reagent,
seemingly because of the partial crossreaction with related homologous adhesion mol-
ecules, such as carcinoembryonic antigen (CEA) (6).
VEGFR-3 is a tyrosine kinase receptor. Its expression is limited almost exclusively to
endothelial cells lining adult lymphatic vessels, as detected by the monoclonal antibody
9D9F9 (20). Although this antibody is highly sensitive for the detection of Kaposi’s
sarcoma, in which it marks even the spindle component of this neoplasm, it is also
reactive with other vascular neoplasms including angiosarcomas, kaposiform hemangio-

endotheliomas, Dabska’s tumor, hobnail hemangioma (Fig. 1), and a few cases of infan-
tile hemangiomas (21,22).
GLUT1 is an erythrocyte-type facilitative glucose transport protein. It is a member of
at least six structurally related proteins, each with a characteristic tissue distribution.
Interestingly, it is present in the endothelium of the microvasculature of blood-tissue
barriers, such as those of the central nervous system, retina, placenta, ciliary muscle, and
endoneurium of peripheral nerves, but it is absent in the vascular endothelium of normal
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Chapter 2 / Special Techniques 9
Fig. 1. Hobnail hemangioma stained with hematoxylin-eosin and VEGFR-3. (A) At scanning
magnification there are dilated vascular structures on the superficial dermis. (B) Many of these
vascular structures show thin walls and are lined by a discontinuous layer of endothelial cells,
giving a lymphatic appearance to the channels. (C) Higher magnification shows that some endot-
helial cells protrude within the lumina with a hobnail appearance. (D) Scanning power view of a
section of the same case stained with VEGFR-3. (E) Higher magnification demonstrates that
endothelial cells lining the lumina express immunoreactivity for VEGFR-3.
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10 Sangüeza and Requena / Pathology of Vascular Skin Lesions
vessels of the skin and subcutaneous tissue (23,24). This marker has also been found in
infantile hemangiomas at different stages of their evolution (Fig. 2). Its specificity for this
category of vascular proliferations is noteworthy, since other lesions including vascular
malformations, pyogenic granulomas, kaposiform hemangioendotheliomas, and epithe-
lioid hemangioendotheliomas do not express this marker (23,24).
2. MOLECULAR TECHNIQUES
During the past few years seminal discoveries have led to valuable applications of new
techniques for the identification and characterization of neoplasms. Techniques such as
the polymerase chain reaction, Southern and Northern blot analysis, and in situ hybrid-
ization are almost routine in many centers. The enhanced knowledge in cancer genetics
is contributing significantly to the prognosis, diagnosis, and treatment of divergent neo-
Fig. 2. Infantile hemangioma stained with hematoxylin-eosin and GLUT-1. (A) Scanning power

view of the lesion showing a cellular proliferation involving the entire thickness of the dermis. (B)
Higher magnification demonstrates numerous vascular channels. (C) Still higher magnification
demonstrates that the vascular channels exhibit a capillary appearance and are lined by a single
layer of endothelial cells.
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