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Abstract

Multicentric reticulohistiocytosis (MRH) is a rare variant of non-Langerhans cell histiocytosis more common in females and characterized by papulonodular cutaneous lesions, and severe and often destructive arthropathy. While cutaneous manifestations can precede or follow arthritis, MRH is not typically known to present with alopecia as a primary finding We describe an unusual case of MRH with an atypical presentation of alopecia secondary to infiltration of follicles by reticulohistiocytes.

A 53-year-old female diagnosed 15 months prior with MRH undergoing treatment with infliximab presented with frontal hairline alopecia with significant follicular dropout without inflammation.  She noted the hair loss had started around the same time as she was diagnosed with MRH following onset with papulonodules involving the ears and extremities accompanied by joint and muscle pain. The differential diagnosis for her alopecia included traction alopecia, frontal fibrosing alopecia, and alopecia areata. A punch biopsy was performed and demonstrated end-stage scarring alopecia.   Aggregates of histiocytes, some with multinucleation, characterized by ground-glass cytoplasm   were identified in the dermis and infiltrating into follicular epithelia. The patient's history of MRH was noted, and given these findings, diagnosis of alopecia due to infiltration by reticulohistiocytosis was rendered.