[Space-occupying lesion of the ribs].

An osteolytic tumor of the 7(th) rib was surgically removed from a 40-year-old patient. Immunohistochemical investigations showed that neither epithelial markers nor B and T cell markers were expressed in the tumor tissue; however, there was strong expression of VS38 and vimentin. These results were compatible with a solitary plasmocytoma of the bone. Further immunohistochemical investigations detected an expression of the melanoma markers S-100 and melan-A. The diagnosis of a metastasis of an amelanotic malignant melanoma could therefore be verified.