Mixed histiocytosis: A case report and published work review.

Histiocytoses are a group of heterogeneous diseases that encompass Langerhans cell histiocytosis and non-Langerhans cell histiocytosis. Cutaneous plane xanthoma is a non-Langerhans cell histiocytic disorder characterized by the presence of yellow-orange plaques on the face, neck, upper trunk and extremities. It can appear in association with several systemic diseases (including dyslipidemias, paraproteinemias, cardiovascular diseases and lymphoproliferative disorders), but is rarely connected with Langerhans cell histiocytoses. Eosinophilic granuloma is one of the clinical entities of Langerhans cell histiocytoses, characterized by skeletal lesions and occurring prominently in children. Mixed histiocytosis, the concomitant occurrence of Langerhans cell histiocytosis and non-Langerhans cell histiocytosis in a single patient, is exceptional. We herein report a case of eosinophilic granuloma in an adult Chinese man who also developed plane xanthoma on his scalp and face, and we also include a published work review of the comorbid cases of eosinophilic granuloma and non-Langerhans cell histiocytosis. To the best of our knowledge, this is the first report on the mixed histiocytosis of cutaneous plane xanthoma and eosinophilic granuloma in China.