Langerhans cell histiocytosis mimicking subcutaneous granuloma annulare: a case report

Langerhans cell histiocytosis (LCH) is characterized by a clonal proliferation of bone marrow-derived Langerhans cells; typically seen in infants and children. The different cutaneous clinical presentation can mimic other diseases. We report a 20 months-old boy with three weeks history of lower limbs cutaneous lesions. Initially, the patient was diagnosed as a subcutaneous granuloma annulare but cutaneous biopsy revealed a dermal infiltration with large histiocytes and positive for S100 and CD1a. LCH mimicking a subcutaneous granuloma annulare was finally diagnosed.