Fig. 6

Histological appearance. Skin biopsy specimen from the sphenoidal bone. a (HE × 140) Besides fatty and striated muscle tissue nodular to diffuse infiltrate of vacuolated and oncocytic (plasmocytoid) as well as mostly xanthomatized (foamy) mononuclear and multinucleate macrophages, which in the first place gives the lesion a more dense eosinophilic appearance, and in the second place a faint colour. b (HE × 200) High power from area indicated in a nicely outlines xanthomatized cells. c (HE × 200) shows oncocytic/plasmocytoid mononuclear cells with dense amphophilic ground glass cytoplasm, occasional eosinophils as well as some Touton and ground glass giant cells, some of the latter with moderate emperipolesis indicated by arrow as well as presence of a prominent brown pigment, which in d (Prussian stain × 200) reveals siderophages, a phenomenon of xanthogranulomas in the literature known as xanthosiderohistiocytosis