Progressive histiocytosis : description of a case of slow-course non-Langerhans cell histiocytosis

We describe the case of a 37-year-old male patient who in 1992 started developing a skin eruption characterized by dark red to red-yellow papulonodular lesions that showed no tendency to spontaneous resolution. Visceral organs were not involved and the lipid pattern was basically normal. Histological examination revealed an infiltrate in the mid and upper dermis mainly consisting of mononucleated and multinucleated histiocytes with an abundant eosinophilic cytoplasm and a ground glass appearance, admixed with numerous xanthomatized cells and Touton and foreign-body giant cells. Immunohistochemical studies showed positivity for CD68 and negativity for CD1a and S-100 protein, whereas at the electron microscopy level the only peculiar finding was the presence of many desmosome-like junctions. The authors believe this to be a borderline form between papular xanthoma and reticulohistiocytosis.