5% of all multiple myelomas manifest as solitary plasmocytomas. The multiple myeloma is the most frequent malignant transformation of the haematopoetic system, with an incidence of 2:100,000 per year. 1% of all solitary plasmocytomas are found in the extremities, accounting for less than one case per year in Germany. In this article we present the case of a fifty year old patient with a solitary plasmocytoma of the shoulder region and discuss the diagnostic and therapeutic procedures involved.