Seborrheic Dermatitis

Pathophysiology

Multifactorial: Involves sebaceous gland activity, Malassezia yeast, and individual immune response
Malassezia yeast: Lipophilic yeast thriving on sebum-rich skin. Produces oleic acid as a metabolite, triggering inflammation in susceptible individuals
Affects areas with highest sebaceous gland density (scalp, face, upper chest, back)
Neurological link: Common in Parkinson disease (possibly from autonomic dysfunction increasing sebum). Prevalence up to 80% in HIV
Cradle cap (infants): Thick, yellowish scales on scalp. Self-limiting, resolves by 8-12 months

Scalp: Flaking (dandruff) ranging from mild to thick, adherent, yellowish scales. Pruritus (itching)
Face: Erythematous patches with greasy scales in nasolabial folds, eyebrows, glabella, around ears
Trunk: Patches on presternal and interscapular areas
Skin folds: Axillae, inguinal folds, inframammary
Greasy, yellowish scales (distinguishes from psoriasis with dry, silvery scales)
Waxing and waning course with seasonal exacerbations (worse in winter)

Unexpected seborrheic dermatitis in a younger adult: Consider screening for Parkinson disease or HIV
Distinguish from psoriasis (dry, silvery scales) and tinea (annular with central clearing)
Active erythematous facial patches: Local contraindication during flares
Dandruff is the mildest form — not a contraindication

Not contagious: No additional IPAC beyond standard hygiene
Scalp involvement: Use disposable covers on face cradle. Ensure thorough cleaning between clients
Facial flares: Active erythematous, scaly patches on face are a local contraindication
Mild dandruff: Not a contraindication. Scalp massage proceeds normally
Lubricant: Avoid heavy, oily products on affected areas (may worsen seborrhea). Fragrance-free preferred
Comorbidity screening: Unexpected onset may warrant neurological or immune screening questions
Client education: Encourage medicated shampoos (zinc pyrithione, ketoconazole) and stress management

NOT contagious — inflammatory reaction to normal skin flora
Greasy, yellowish scales distinguish from psoriasis (dry, silvery) and tinea (annular with clearing)
High prevalence in Parkinson disease and HIV
Dandruff is the mildest form. Cradle cap is the infant form
Active facial flares are a local contraindication. Mild scalp involvement is not

Seborrheic dermatitis is a chronic inflammatory condition associated with Malassezia yeast in sebum-rich areas
Greasy, yellowish scales in scalp, nasolabial folds, eyebrows, and central chest are characteristic
Not contagious. Dandruff is the mildest form. Cradle cap is the self-limiting infant form
Significantly more prevalent in Parkinson disease and HIV/AIDS
Active facial flares are a local contraindication. Mild scalp involvement is not