Follicular keratosis

Specialty: Skin.

• Darier follicular keratosis
• crusted follicular keratotic papules

Why it occurs

• Darier-White disease (autosomal dominant genetic disorder characterized by mutations in the ATP2A2 gene that alters intracellular calcium homeostasis and causes epidermal acantholysis)
• Severe and chronic vitamin A deficiency (phrynoderma, characterized by dry keratotic follicular papules on extremities)
• Severe generalized keratosis pilaris of genetic origin
• Adverse effect of antineoplastic drugs that inhibit the epidermal growth factor receptor (EGFR)
• Chronic occupational exposure to chlorinated hydrocarbons or industrial cutting oils.

Initial workup

Skin biopsy of an active papule to confirm the presence of characteristic follicular dyskeratosis (round bodies and pimples in the stratum spinosum and corneum) associated with suprabasal acantholysis. Analytical determination of serum vitamin A levels if nutritional deficiency (phrynoderma) is suspected.

Standard management

• Acitretin — systemic retinoid of choice to normalize keratinization and epidermal cohesion in Darier's disease, doses of 10 to 25 mg daily orally, with strict control of lipid and hepatic profile
• Oral isotretinoin — systemic retinoid alternative useful to reduce follicular hyperkeratosis
• Tretinoin cream 0.05% — applied locally to mild, non-inflamed lesions to promote exfoliation of the horny plug
• Topical clindamycin or mupirocin (indicated for the preventive control of secondary bacterial colonization on Darier scabs).