An 8-month-old has a greasy, scaling, seborrhea-like rash on the scalp and behind the ears that has failed two months of antifungal therapy. On review she looks pale and lethargic, with petechiae over the trunk and hepatosplenomegaly. What is the next best step?

• A Skin biopsy for CD1a staining ✓
• B Increase topical antifungal potency
• C Serum IgE level
• D Trial of topical corticosteroid

Explanation

Langerhans cell histiocytosis classically mimics refractory seborrheic dermatitis or cradle cap, and the red flags here are purpuric petechiae within the eruption, systemic symptoms and organomegaly. Diagnosis is made by skin biopsy showing CD1a and S100 positive Langerhans cells with Birbeck granules on electron microscopy. Persisting with antifungals or steroids alone delays treatment of a potentially multisystem disease.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.