Multicentric Reticulohistiocytosis Induced Alopecia: A Clinical Case Report.

Multicentric reticulohistiocytosis (MRH) is a systemic inflammatory disease with dermatologic, musculoskeletal, and mucosal manifestations with symmetric erosive arthritis and reddish-brown papulonodular lesions. Histopathologic findings include epithelioid and multinucleated histiocytes with ground glass cytoplasm. We demonstrate the case of a 52-year-old female who presented with scattered red-brown papules, finger swelling, and muscle pain. Biopsy demonstrated a dermal proliferation of large mononucleated and multinucleated histiocytes with dense, pink, oncocytic cytoplasm, consistent with MRH. Patient initiated prednisone, methotrexate, folic acid, and adalimumab. On follow-up, the patient reported progressive hair loss confined to the frontal scalp. Physical exam showed moderately well-defined, pauci-inflammatory alopecic patches with follicular drop-out and negative hair pull test. A punch biopsy from the scalp demonstrated a marked decrease in follicular units associated with aggregates of histiocytes in the upper dermis with infiltration of the follicular epithelium, some multinucleate, with abundant two-toned ground-glass cytoplasm. A diagnosis of alopecia secondary to follicular involvement by reticulohistiocytosis was made. To our knowledge, this is the first reported case of alopecia secondary to MRH in the literature.