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Case Reports

Abstract

Generalized eruptive histiocytoma (GEH) is a rare non-Langerhans cell histiocytosis typically characterized by hundreds of symmetrically distributed erythematous to yellow-brown papules and plaques. It typically affects adults aged 20-50 and has a benign prognosis. Here we present a case of a 35-year-old male with several scattered, erythematous, indurated papules coalescing into plaques on the face and scalp, which later progressed to the trunk and upper extremities six weeks later. The patient had previously failed treatment with topical corticosteroids.  A biopsy was obtained, and histopathologic examination demonstrated nodular and diffuse granulomatous inflammation in the dermis with foamy histiocytes, touton and Langhans giant cells, plasma cells, and eosinophils. PAS and FITE stains were negative and laboratory tests including flow cytometry, serum and urine electrophoresis, CMP, and CBC were all within normal limits. Given these findings, a diagnosis of GEH was made. The patient was offered treatment with hydroxychloroquine and narrowband ultraviolet B therapy. The patient opted to pursue phototherapy alone with subsequent improvement in his skin lesions. This case highlights the significance of a thorough dermatopathological evaluation in diagnosing and managing rare histiocytic disorders of the skin.