Chapter 053. Eczema and Dermatitis (Part 10) pptx

Chapter 053. Eczema and
Dermatitis
(Part 10)

Ecthyma is a variant of impetigo that causes punched-out ulcerative lesions.
It may result from neglected or inadequately treated impetigo. Treatment of both
ecthyma and impetigo involves gentle debridement of adherent crusts, which is
facilitated by the use of soaks and topical antibiotics, in conjunction with
appropriate oral antibiotics. Furunculosis is also caused by S. aureus, and this
disorder has gained prominence in the last decade because of CA-MRSA. A
furuncle, or boil, is a painful, erythematous, nodule that can occur on any
cutaneous surface. The lesions may be solitary but are most often multiple.
Patients frequently believe they have been bitten by spiders or insects. Family
members or close contacts may also be affected. Furuncles can rupture and drain
spontaneously or may need incision and drainage, which may be adequate therapy
for small solitary furuncles without cellulitis or systemic symptoms. Whenever
possible, lesional material should be sent for culture. Current recommendations for
methicillin-sensitive infections are β-lactam antibiotics. Therapy for CA-MRSA
was discussed previously (see "Atopic Dermatitis"). Warm compresses and nasal
mupirocin are helpful therapeutic additions. Severe infections may require IV
antibiotics.
Table 53-5 Common Skin Infections

Clinical
Features
Etiologic
Agent
Treatmen
t
Impetigo Honey-
colored

crusted papules,
plaques, or bullae
Group A
Streptococcus
and
Staphylococcus
aureus
Systemic
or topical
antistaphylococc
al antibiotics
Dermatophytos
is
Inflammatory
or noninflammatory
annular scaly plaques;
may have hair loss;
groin involvement
Trichophyto
n,
Epidermophyton,
or Microsporum

Topical
azoles, systemic
griseofulvin,
terbinafine, or
spares scrotum;
hyphae on KOH
preparation

sp. azoles
Candidiasis Inflammatory
papules and plaques
with satellite pustules,
frequently in
intertriginous areas;
may involve scrotum;
pseudohyphae on
KOH preparation
Candida
albicans
and other
Candida species
Topical
nystatin or
azole
s; systemic
azoles for
resistant disease
Tinea
versicolor
Hyperpigment
ed or hypopigmented
scaly patches on the
trunk; characteristic
mixture of hyphae
and spores on KOH
preparation
("spaghetti and
Malassezia

furfur

Topical
selenium sulfide
lotion or azoles
meatballs")
Erysipelas and Cellulitis
See Chap. 119
Dermatophytosis
Dermatophytes are fungi that infect skin, hair, and nails and include
members of the genera Trichophyton, Microsporum, and Epidermophyton. Tinea
corporis, or infection of the relatively hairless skin of the body (glabrous skin),
may have a variable appearance depending on the extent of the associated
inflammatory reaction (see Fig. 52-11). Typical infections have an annular
appearance that patients refer to as "ringworm." Deep inflammatory nodules or
granulomas occur in some infections—especially in those infections
inappropriately treated with mid- to high-potency topical glucocorticoids.
Involvement of the groin (tinea cruris) is more common in males than females. It
presents as a scaling, erythematous eruption sparing the scrotum. Infection of the
foot (tinea pedis) is the most common dermatophyte infection and is often chronic;
it is characterized by variable erythema, edema, scaling, pruritus, and occasionally
vesiculation. Involvement may be widespread or localized but generally involves
the web space between the fourth and fifth toes. Infection of the nails (tinea
unguium or onychomycosis) occurs in many patients with tinea pedis and is
characterized by opacified, thickened nails and subungual debris. The distal-lateral
variant is most common. Proximal subungual onychomycosis may be a marker for
HIV infection or other immunocompromised states. Dermatophyte infection of the
scalp (tinea capitis) has returned in epidemic proportions, particularly affecting
inner-city children, but it also affects adults. The predominant organism is T.
tonsurans, which can produce a relatively noninflammatory infection with mild

scale and hair loss that is diffuse or localized. T. tonsurans can also cause a
markedly inflammatory dermatosis with edema and nodules. This latter
presentation is a kerion.
The diagnosis of tinea can be made from skin scrapings, nail scrapings, or
hair by culture or direct microscopic examination with potassium hydroxide
(KOH). Nail clippings may be sent for histologic examination with periodic acid
Schiff (PAS) stain.