DermatologyTier 1Disease (DEADMAN)

Dermatitis - seborrheic

Description

Chronic relapsing papulosquamous dermatitis of sebum-rich areas - scalp, eyebrows, nasolabial folds, ears, chest
Greasy, yellowish, ill-defined scale on an erythematous base - distinguishes from psoriasis (well-demarcated, silvery)
Infantile form ("cradle cap") - self-limiting, distinct natural history from adult disease

~1-3% of the general population; peaks in infancy, and again in adulthood 30-60 years
M>F in adults
Markedly increased prevalence and severity in HIV/immunosuppression and Parkinson's disease

Malassezia yeast (skin commensal) proliferation in sebum-rich skin -> irritant lipid metabolites -> inflammatory response, not a true infection
Contributing factors: sebum production, individual inflammatory/barrier response to Malassezia (not simply yeast load)
Triggers/exacerbants: stress, cold weather, immunosuppression, neurological disease (Parkinson's - thought related to autonomic sebum dysregulation and reduced facial movement/hygiene)

Clinical - diagnosis usually made on distribution and appearance

Scalp (dandruff at the mild end), eyebrows, glabella, nasolabial folds, retroauricular, presternal, flexures
Infants - cradle cap: greasy scale on the scalp/vertex, usually otherwise well

Differential

	Discriminator
Psoriasis	Well-demarcated, silvery scale, extensor surfaces, nail changes
Atopic dermatitis	Intensely itchy, flexural, personal/family atopy
Tinea capitis/faciei	Asymmetric, scrape/culture positive

Widespread, severe, or treatment-refractory seborrhoeic dermatitis in an adult - consider HIV testing

A. Scalp

Antifungal shampoo (ketoconazole, selenium sulfide, zinc pyrithione) - first-line, regular use
Topical corticosteroid (mild-moderate potency lotion) for inflamed flares

B. Face/body

Topical antifungal (ketoconazole cream) +/- mild topical corticosteroid for short-course flare control
Topical calcineurin inhibitors (tacrolimus/pimecrolimus) - steroid-sparing option for facial disease given risk of steroid atrophy/rosacea-like changes with prolonged facial steroid use

C. Infantile (cradle cap)

Usually self-limiting; emollient/mineral oil to soften scale, gentle brushing, mild antifungal shampoo if persistent - reassurance is often the main intervention

D. Maintenance

Chronic relapsing course - intermittent antifungal shampoo/cream use for long-term control, not a one-off cure

HIV/immunosuppression - more extensive, severe, treatment-resistant disease
Parkinson's disease and other neurological conditions affecting facial movement
Psychiatric conditions, institutionalisation (reduced hygiene/mobility)
Rosacea - can coexist, complicates facial treatment choice

Infantile form - typically resolves by 6-12 months without treatment
Adult form - chronic, relapsing-remitting, often lifelong with periods of quiescence and flare
Secondary bacterial/fungal infection uncommon but possible with excoriation
Significant cosmetic and quality-of-life impact when facial/visible sites affected chronically

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