Rib plasmacytoma and IgA multiple myeloma with hyperviscosity syndrome.

Solitary bone plasmacytoma (SPB) can progress to generalized myeloma if not treated early. The elderly population is increasing and delays in diagnosis of plasma cell malignancies are frequent among them. Hyperglobulinemia of multiple myeloma (MM) plays a role in hyperviscosity syndrome (HVS). A 65-year-old woman with hypertension and diabetes mellitus was admitted due to loss of appetite, muscle weakness, breathlessness and discrete expectoration, without fever. Chest X-ray showed an abnormal shadow projection on the right lung field, while computed tomography (CT) revealed an osteolytic mass at the sixth rib. There were more than 50% of plasma cells in the bone marrow samples and high IgA levels according to serum electrophoresis. Rib plasmacytoma and overt IgA-producing myeloma with HVS were diagnosed, but treatment was unsuccessful. Case studies may enhance the awareness about this ominous condition, which may develop unnoticed, particularly in elderly patients with renal insufficiency, and can pose difficulties with diagnosis in primary care settings.