# Seborrhoeic Dermatitis > Seborrhoeic dermatitis for NEET-PG Medicine: Malassezia-driven scaling in sebum-rich sites, ketoconazole shampoo ladder, cradle cap and when to test for HIV. - Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/seborrhoeic-dermatitis - Exam / course: NEET-PG · Subject: Medicine - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Seborrhoeic Dermatitis", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/seborrhoeic-dermatitis ## Direct answer Greasy, yellow-white scale sitting precisely where sebum flows — the scalp as dandruff, the nasolabial folds, eyebrows, glabella, central chest and skin folds — defines seborrhoeic dermatitis, an inflammatory reaction to Malassezia yeasts rather than a classical infection: yeast lipases liberate fatty acids that irritate susceptible skin. First-line treatment is ketoconazole 2% shampoo used on scalp and face twice weekly until clear, then weekly for maintenance, with short courses of mild topical corticosteroid or a topical calcineurin inhibitor for inflamed facial flares. The disease relapses whenever treatment stops — maintenance counselling is part of the prescription. Severe, refractory or atypical presentations should prompt HIV testing and screening for Parkinson disease; infancy brings the self-limiting cradle cap. ## What you must remember - **Distribution is the diagnosis:** sebum-rich terrain — scalp, nasolabial folds, eyebrows, beard area, glabella, presternal chest, axillary and inguinal folds; margin sharply demarcated with greasy scale on dull erythema. - **Mechanism:** Malassezia (globosa and restricta) colonises everyone, but lipase-released free fatty acids ignite inflammation only in susceptible hosts — hence antifungals help though the yeast is not an invader. - **Treatment ladder:** ketoconazole 2% shampoo or ciclopirox twice weekly for two to four weeks, then weekly-to-fortnightly maintenance; mild topical steroid (hydrocortisone 1%, or mometasone briefly) for flares; tacrolimus or pimecrolimus for steroid-sparing facial control; oral itraconazole for severe disease. - **Infancy:** cradle cap — yellowish scale over the vertex with self-resolution; emollients and dilute ketoconazole shampoo suffice; avoid potent steroids. - **The two associations worth marks:** HIV (severe, extensive, treatment-recalcitrant seborrhoeic dermatitis is an indicator to offer testing) and Parkinson disease (striking seborrhoea years before or after diagnosis); spinal cord injury adds a third, weaker link. - **Maintenance truth:** relapse follows cessation within weeks to months in most patients — schedule the maintenance day rather than promising cure. - **Differential anchors:** psoriasis (well-demarcated extensor plaques, elbow-knee symmetry, nail pitting), tinea (KOH-positive, annular with active edge), atopic dermatitis (flexural, dry, itch-dominated), rosacea (no scale, no greasiness). ## Clearing a resistant case step by step A 30-year-old man returns for the third time with "dandruff that defeats every shampoo". Work him properly. Step one: confirm the diagnosis — inspect nasolabial folds, eyebrows and presternal chest for the same greasy scale, and scrape the edge for KOH to exclude tinea, which antifungal-shampoo misuse can partially treat and blur. Step two: check he is actually using ketoconazole correctly — applied to the scalp, left five minutes, extended to the face — twice weekly for four weeks, not a cosmetic two-second rinse. Step three: add a short course of hydrocortisone 1% to the face to settle inflammation, planning withdrawal within two weeks. Step four: fix the maintenance schedule — weekly ketoconazole indefinitely interrupted only by long clear spells. Step five: reassess severity — if the disease is unusually extensive, explosive or refractory despite correct therapy, offer HIV testing with counselling, and examine for parkinsonian features in older patients. The reasoning to articulate: severity itself is a diagnostic sign here. Ordinary seborrhoeic dermatitis is a nuisance; extraordinary seborrhoeic dermatitis is a clue to an immunological or neurological shift, and the two questions (HIV status, neurological examination) cost nothing. ## The Indian context India's heat and humidity thicken the seborrhoeic burden, and monsoon flares are real enough for patients to time their own recurrences. The practical Indian realities: ketoconazole 2% shampoo is cheap and effective, yet patients cycle instead through antiseptic and cosmetic shampoos that contain no antifungal; coal-tar preparations linger in practice with mess but modest evidence; and potent steroid-combination creams bought over the counter produce telangiectatic, steroid-dependent faces that then need unwinding. The HIV link deserves local emphasis — India's testing programme makes the offer straightforward, and marked seborrhoeic dermatitis at a low CD4 count is a recognised presenting feature of advanced HIV in Indian series. In Parkinson disease clinics, seborrhoea is among the most common non-motor skin signs, so a dermatology referral occasionally becomes the first neurological clue. ## Frequently asked questions ### Which organism underlies seborrhoeic dermatitis? Malassezia species — commensal yeasts whose lipase-released fatty acids provoke inflammation in susceptible skin rather than causing classical infection. ### What is first-line therapy? Ketoconazole 2% shampoo twice weekly until clear then weekly maintenance, with short mild topical steroid or calcineurin inhibitor for inflamed facial flares. ### Why test for HIV in severe seborrhoeic dermatitis? Explosive, extensive or treatment-refractory disease is a recognised marker of advanced HIV and should trigger counselling and testing. ### What is cradle cap? Yellowish, greasy scale over the infant scalp — a self-limiting neonatal form managed with emollients and dilute antifungal shampoo. ### How does seborrhoeic dermatitis differ from psoriasis? Seborrhoeic disease favours sebum-rich folds with greasy fine scale; psoriasis favours extensor elbows and knees with thick silvery scale and nail pitting.