Generalized Eruptive Histiocytosis: A Case Report in an Elderly Person With a Positive Rheumatoid Factor

We report a case of generalized eruptive histiocytosis (GEH) in a 63-year-old woman with unique clinical and histopathological characteristics. She presented with a papular eruption, mainly on the dorsa of the hands and forearms. Histopathology showed a nodular dermal histiocytic lesion positive for S100, CD45, and CD163 staining in larger histiocytes. EMA, CAM 5.2, and AE1/AE3 stains were negative. We discuss the differential diagnoses and stress that GEH is usually benign, with, in this case, spontaneous regression. However, cases should be evaluated carefully for the possibility of underlying disease, and follow-up is mandatory to evaluate their evolution into other types of more aggressive histiocytosis.