Basil J. Zitelli, M.D.
Children’s Hospital of Pittsburgh
COMPARATIVE DERMATOLOGY NOTES
3. For such a common problem that has been described since the 19th
century, Hill and Sultzberger in 1935 characterized it as a clinical entity.
a. 7/1000 in the US, 3%-5% of children from 6 mo to 10 yr
b. Acute (erythema, scaly, vesicle, crusts)
Chronic (scaly, lichenified, pigment changes)
c. Infancy - initially red, pruritic papules/plaques, diaper area usually
d. Childhood - circumscribed erythematous scaly lichenified plaques,
frequent secondary infection
4. Pruritus, irritability are common associated symptoms
5. Scabies - intensely pruritic, irritable, can be diffuse and more papular
a. Sarcoptes scabiei infestation: female mite burrows and lays eggs
resulting in burrows, may involve genital area, palms and soles
6. Wiskott Aldrich - X-linked recessive, recurrent infections that begin in
a. Inability to form antibody to bacterial polysaccharide antigens is the
most common immune defect, but some patients may have a partial
T-cell defect as well.
C. Childhood - usually begins between 4y-10y
1. Dry, scaly, pruritic, localized to wrists, ankles, antecubital and
popliteal fossae; May involve the hands with cracking, drying and
scaling of palmar surface and excoriations and lichenification of the
dorsum of hand
2. Nummular eczematous dermatitis - discrete coin shaped red patches
in patients with eczema, beginning as tiny papules and vesicles forming
confluent patches, pruritic. with lack of central clearing
a. Psoriasis - red , demarcated plaques with dry silvery scale tend to be
located on extensor surfaces of extremities, scalp and buttocks.
In infants may present as diaper dermatitis
(1) Thickened skin produced by increased epidermal growth, there
are areas of thin skin between epidermal layers with scale close to
surface of skin; scale removed results in bleeding point called
Auspitz sign - hallmark of psoriasis.
(2) Skin of palms may be markedly thickened with silvery fissuring
of palmar creases
b. Tinea corporis - infection of the glabrous (non hairy) skin; pruritic,
annular lesion with central clearing and active vesicular border.
(1) Differentiate from atopic dermatitis because of its propensity to
autoinoculate and central clearing.
II. Seborrhea - red scaly eruption occurring primarily on hair-bearing and
intertriginous areas: scalp, eyebrow, eyelashes, perinasal, presternal,
postauricular area and intertriginous areas. Pityrosporum and Candida
have been implicated as causative agents
A. Greasy, salmon-colored scaly dermatitis, usually pruritic
B. Differentiate form histiocytosis X and T. Corporis
1. Histiocytosis X - proliferative disorder of Langerhans type cells with
specific cytological markers. Skin infiltration is most common in Letterer-
Siwe disease, beginning as diffuse, papular scaly eruption; differs from
seborrheic dermatitis by infiltrated crusted petechial rash, frequently
involving the trunk, associated with chronic ear infection, draining ears
I. Tinea corporis - found in any age group, usually acquired from an infected
domestic animal (Microsporum canis) or by direct human contact
(Trichophyton, Microsporum , and Epidermophyton species)
A. Differentiate from granuloma annulare
1. Depth of lesion - dermal infiltration of lymphocytes around altered
collagen, epidermis is normal, may have slight erythema
2. Begins as nodule or papule, gradually extending peripherally to form
a ring, found commonly on extensor surfaces of lower legs, feet, fingers,
3. Usually asymptomatic and resolves spontaneously within a few
months to years.
B. Differentiate from pityriasis rosea, herald patch
1. Self-limited disorder which can occur at any age but more often
2. adolescents and young adults.
3. Eruption begins with a herald patch - large oval lesion slightly scaly
sometimes with central clearing.
4. Prodrome of malaise, headache and mild constitutional features may
precede the rash.
5. 5-10 days later smaller lesions appear on the trunk , papules to ovals
with scale, creating AChristmas tree@ pattern.
6. Rash peaks in several weeks and fades over 4-6 weeks
7. Consider secondary syphilis rash which may be a truncal scaly rash in
Christmas -tree distribution, but may involve the hands and feet.
C. And while we are talking about palmar rashes ...
1. Measles - close to being eradicated in the U.S. ; about 100 cases in
the U.S. last year, most imported
a. Cough, conjunctivitis, coryza
b. Rash preceded by Koplik spots
c. Rash begins in hairline and spreads cephalocaudally
d. Palms/soles involved
2. Drug eruption - many different types, morbilliform accounting for more
a. Erythematous macules and papules begin to erupt on face and trunk
5- 14 days after initiation of a drug and spreads to the extremities
over several days; may involve palms and soles
A. Transient, well-demarcated wheals, usually pruritic, often as part of an
acute, IgE-mediated hypersensitivity reaction. May occur anywhere and
any size; may leave central clearing leading to annular, polycyclic and
1. Acute urticaria - <6 wks, triggered by hypersensitivity to foods, drugs,
insect bites, contact antigens, infection (strep, hepatitis) or inhaled
2. Physical agents: cold, heat, water, exercise, or mechanical pressure.
3. Dermatographism is common
1. Hereditary angioedema - angioedema differs from urticaria by involving
deeper layers of the skin including subcutaneous tissues
a. H. A. - autosomal dominant C1 inhibitor deficiency involving lips,
tongue and airway, lacks urticaria, recurrent GI colic
2. Mastocytosis - collection of mast cells that release histamine when
stimulated causing wheal and flare reaction.
a. May have numerous brownish plaques in the skin and GI involvement -
3. Erythema marginatum - not pruritic
a. Gyrate urticarial plaques formed by coalescence of individual pruritic
urticarial lesions that may mimic erythema marginatum
4. Urticarial / erythema multiforme-like reaction
a. Constellation of urticarial lesions, periarticular swelling, extremity
angioedema - usually in association with upper respiratory tract
infection, sulfa-containing antibiotics, or cefaclor
b. Lesions nonpruritic or mildly pruritic creating target or gyrate shapes
but no vesiculation, migratory stocking/ glove angioedema which is
painful (suggesting hypersensitivity type III reaction rather than
type I )
5. Erythema multiforme (EM) - reactive erythema with symmetrical
distribution, dorsum of hands and feet, palms and soles.
a. Dusky red macules or erythematous wheals evolving into target -
shaped lesions may simulate urticaria but less pruritic
b. May vesiculate or become bullous
6. Stevens - Johnson syndrome (SJS)
a. Rarely EM may progress to SJS with mucus membrane and epidermal
necrosis and shedding
b. Constitutional features of fever, cough, sore throat, vomiting, diarrhea,
chest pain and arthralgias are common
c. Vesiculation and bullae appear early, along with mucus membrane
involvement of oral cavity conjunctivae, and genital mucus
d. Toxic epidermal necrolysis - (TEN) may be the most fulminant form of
(1) Similar inciting agents as SJS
(2) Begins as generalized erythroderma followed by sloughing of the
skin and mucus membrane involvement
(3) Nikolsky sign indicating epidermal layer cleavage (epidermal-
dermal junction, differing from cleavage plane in staphylococcal
scalded skin syndrome which is between the upper and mid
III. Vascular tumors and malformations
A. Vascular anomalies - 2 types
1. Hemangiomas - benign tumors characterized by rapid proliferative
phase lasting 8 -10 months with slow involution over several years,
comprised of proliferating endothelial cells
a. 1% of newborns may have hemangiomas and up to 10% of children
under 1 yr of age - most appearing by 4 weeks of age
2. Vascular malformations are dysplastic vessels without endothelial
proliferation, subdivided into vessel type ( capillary, venous, arterial,
lymphatic or combination) and flow (high flow or low flow)
a. Salmon patches occur in 60-70% of newborns usually at nape of neck,
glabella, forehead or upper eyelids.
b. At birth 0.2-0.3% of children have port wine stains (PWS) which tend
B. Hemangiomas - alteration in balance of endothelial cell proliferation and
inhibitors of vascular growth.
1. Proliferative stage - high levels of basic fibroblast growth factors,
vascular endothelial growth factors and a variety of other stimulators of
2. Involuting hemangiomas exhibit tissue inhibitor metalloproteinase and
mast cells, interferon alpha (2α and 2β), thalidomide, angiostatin and
other inhibitors of angiogenesis.
3. Natural history of hemangiomas in non-vital areas is spontaneous
involution: 25% by 2 yr, 40-50% by 4 yr, 60 -75% by 6 yr, 95% by
a. RICH (rapidly involuting congenital hemangioma), NICH (non-
involuting congenital hemangioma)
4. Extensive facial hemangiomas raise suspicion associated anomalies
and other tissue involvement.
a. PHACES - Posterior fossa malformations, large Hemangiomas of the
face, Arterial abnormalities, Coarctation of the aorta and Cardiac
defects, and Eye abnormalities, Sternal abnormalities
b. Hemangiomas of the cervicofacial areas may also involve the airway,
especially with a beard distribution, presenting with biphasic stridor,
normal voice and no swallowing difficulties.
(1) Scoring system = 1 point for each: left preauricular area, right
preauricular area, chin, lower lip, anterior neck.
(a) 4 points = 63% chance of symptomatic airway involvement
c. Extensive craniofacial hemangiomas may be associated with
anomalies of cerebral arteries and aortic arch, orbital and periorbital
5. Treatment - many modalities including:
a. Flashlamp pulsed dye laser, topical and systemic steroids, intralesional
steroid injections, embolization and excision
c. Experimental modalities - thalidomide, COX2 inhibitors, doxycycline,
metalloproteinase inhibitors, angiostatin
C. Vascular malformations - port wine stains (PWS) persist unchanged
during childhood, tend to darken in adolescence and adulthood
1. Sturge-Weber syndrome - PWS at birth involving V1, may have
ipsilateral leptomeningeal vascular malformations and ophthalmic
involvement with choroid angioma and glaucoma.
a. Occurs in about 10% of patients with V1 PWS manifesting by 1 yr of
age with seizures
2. Treatment with flashlamp pulsed dye laser has revolutionized
treatment of PWS
A. Suntan - tan lines obvious
1. Addison disease - diffuse hyperpigmentation; increased pigment of
scars, gingiva, palmar creases; thin body habitus
a. ACTH deficiency - no hyperpigmentation
B. Juvenile xanthogranuloma - yellowish nodule with infiltration and
proliferation of histiocytes, grows rapidly in infants and young children,
resolves spontaneously, are not associated with lipid abnormalities
C. Multiple JXG may be associated with non-traumatic hyphema.
D. Linear nevus sebaceous may have 10%-15% risk of malignancy and if
mid facial may be associated with seizures and mental retardation
E Xanthoma - related to hypercholesterolemia, usually involving bony
prominences or tendons, disappear after successful treatment or liver
1. Mongolian spots - slate gray dermal pigmentation, seen frequently in
2. Normal toddler bruises
3. Petechiae, purpura
a. Henoch-Schoenlein purpura
4. Patterned bruises
a. Unusual location - trunk, head, face
b. Patterns of weapons - chain, rope, hand
d. Coining, cupping, pinching
e. Bleeding from protein-energy malnutrition
(1) Acral rash - acrodermatitis enteropathica, biotin deficiency
G. Effects of immune deficiency
1. Thrush, candida dermatitis, onychomycosis
3. Kaposi sarcoma
4. White cell defects
7. Clubbing from interstitial pneumonitis
a. Differential clubbing from differential cyanosis - reversed shunting
through a patent ductus arteriosus in a patient with pulmonary
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