A 76-year-old man with a 14-year history of monoclonal gammopathy of undetermined significance (MGUS, IgG lambda) suffered a traumatic fracture of his right humerus, requiring internal fixation with an intramedullary nail. Three months later, several rapidly growing tumours developed at the sites of the recent surgery (left and centre). Fine needle aspirate of the tumours demonstrated that these were plasmacytomas (IgG lambda). Bone marrow aspirate and biopsy demonstrated 60% infiltration with plasma cells, indicating transformation to multiple myeloma. The patient was treated using local radiotherapy, with resolution of the lesions. However, within 1 month, further similar lesions developed in a sterniotomy scar where the patient had undergone cardiac surgery 14 years previously (right). Despite further treatment with local radiotherapy, intravenous pamidronate, and oral melphalan and prednisolone, the patient's general medical condition deteriorated and he died.
The occurrence of malignant tumours in scar tissue is a well-recognized phenomenon. The majority of cases describe the development of squamous cell carcinoma in burn scars or in chronic wounds (Marjolin's ulcer), or tumour cell ‘seeding’ along the needle track of a biopsy site. To our knowledge, plasmacytoma with a predilection for scar tissue has not been previously described.