Definition of Seborrheic Dermatitis : chronic superficial benign inflammatory dermatosis reaching particularly hairy areas: scalp, eyebrows, face, mediothoracique region.
Etiology : Risk Factors: Parkinson's Disease, cancer of upper aerodigestive tract, HIV Infection, Stress
Pityrosporum ovale (agent of pityriasis versicolor) may be a contributing factor.Genetic factors: family history frequentlyPsychological factors: frequent worsening of seborrheic dermatitis during stress or intercurrent illness.
Activity of the dermatosis a similar pattern to the activity of the sebaceous glands in childhood and adolescence.
Clinical signs :
1. For children - Helmet scaly scalp with erythema discreet - Intertrigo erythematous scaly axillary folds and creases of the neck - Dermatitis seat - Appears in general at the age of 1 month and disappears between 8 and 12 months
Treatment: - Scalp: Frequent shampooing (2 to 3 times a week) to selenium sulfide or zinc pyrithione and imidazole lotion - Face: emollients (cold cream) and possibly imidazole cream.Evolution: in children, seborrheic dermatitis usually disappears at the age of 6 or 8 months.
2 - Adults - plates ill-defined erythematous, scaly with greasy scale arranged bilaterally symmetrical seborrheic areas: scalp, eyebrows and eyelashes, nasolabial folds, ears and retroauricular folds, presternal region and cleft - Evolution chronic with extensive winter.
Treatment Seborrheic Dermatitis : - scalp: Selenium sulfide shampoos or pyrithione zinc alternating with tar shampoos may be associated with salicylic acid. Lotions with steroids low activity level 3 or 4 times a week - Face and presternal region: imidazole cream or gel daily for 2 to 4 weeks. Corticosteroids of low activity forms when rebels for 2 to 4 weeks, then progressive spacing.Evolution: in adults, the course is chronic with flares winter but local treatments can usually control it well.
Differential Diagnosis :
Simple pityriasis of the scalp (no inflammatory cells)Atopic dermatitis (often difficult to distinguish in children)Psoriasis (involvement of knees and elbows. Achievement of nails. Psoriasis of the scalp is often more limited than seborrheic dermatitis with scaly patches and infiltrated.)CandidaTinea or ringworm of the folds (should be suspected in case of failure of conventional treatments or Alopecia)Eczema of the ear or otitis externa (ear for locations)RosaceaDiscoid lupus erythematosusLangerhans cell histiocytosis (perform histology on failure of conventional treatment in children, in case of developments dragging or purpuric papules folds)Pathology in eczematous dermatitis nonspecific (unnecessary biopsy, unless a suspected LCH)