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Skin-nontumor / Clinical Dermatology

Other dermatoses

Seborrheic dermatitis


Reviewer: Mowafak Hamodat, MB.CH.B, MSc., FRCPC (see Reviewers page)
Revised: 5 September 2011, last major update August 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Definition
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● Nummular eczema (silver dollar-sized patches) to generalized exfoliative dermatitis (severe atopic dermatitis) to large vesicles on palms and soles (dyshidrosis)
● Not due to any known agents, although associated with irritant contact dermatitis
● One of the most common cutaneous manifestations of AIDS, affecting 2080%
● Also associated with Parkinson's disease, epilepsy, congestive heart failure, obesity, chronic alcoholism, Leiner's disease (exfoliative dermatitis of infancy) and zinc deficiency
● May occur as reaction to arsenic, gold, chlorpromazine, methyldopa and cimetidine

Treatment
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● Keratolytic agents, some over the counter
● Anti-inflammatory products, such as topical corticosteroids, have some effect

Clinical description
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● Erythematous scaling papules and plaques, sometimes with a greasy yellow appearance, with a characteristic distribution on scalp, ears, eyebrows, eyelid margin, and nasolabial area the so-called "seborrheic areas"

Clinical images
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Various images

Micro description
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● Acute, subacute or chronic spongiotic dermatitis
● In acute lesions, there is focal, usually mild, spongiosis with overlying scale crust containing a few neutrophils; the crust is often centered on a follicle; papillary dermis is mildly edematous; blood vessels in superficial vascular plexus are dilated and there is mild superficial perivascular infiltrate of lymphocytes, histiocytes and occasional neutrophils; some exocytosis of inflammatory cells but not as prominent as in nummular dermatitis
● In subacute lesions, there is also psoriasiform hyperplasia, initially slight, with mild spongiosis and the other changes already mentioned; numerous yeast-like organisms can usually be found in the surface keratin
● Chronic lesions show more pronounced psoriasiform hyperplasia and only minimal spongiosis; sometimes the differentiation from psoriasis can be difficult but the presence of scale crusts in a folliculocentric distribution favors seborrheic dermatitis

Additional references
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eMedicine

End of Skin-nontumor / Clinical Dermatology > Other dermatoses > Seborrheic dermatitis


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