Solitary osteosclerotic plasmacytoma: association with demyelinating polyneuropathy and amyloid deposition

A 51-year-old man presented with a 1-year history of polyneuropathy necessi tating the use of a wheelchair. Initial diagnosis was idiopathic chronic in flammatory demyelinating polyneuropathy (CIDP) and associated monoclonal ga mmopathy. Investigations for multiple myeloma, including bone marrow aspira tion and biopsy, were negative. What was initially felt to be an incidental osteosclerotic focus noted on the radiographic bone survey was eventually shown to be a solitary osteosclereotic plasmacytoma with associated amyloid . This dramatically altered treatment. This case emphasizes the importance of including osteosclerotic plasmacytom a in the differential diagnosis of a focal sclerotic bone lesion in the cli nical setting of polyneuropathy. These lesions are less likely to progress to multiple myeloma than lytic plasma cell neoplasms, and the presence of p olyneuropathy often results in earlier diagnosis and treatment with enhance d prospect of cure. The finding of amyloid deposition within the osteoscler otic lesion may be of prognostic importance.