Association of Multiple Myeloma and Giant Cell Arteritis – A Case Report

Autoimmune diseases (AID) have been associated with a variety of lymphoproliferative disorders. Multiple myeloma (MM), one of the most common haematologic malignancies characterized by clonal proliferation of bone marrow plasma cells, has been associated with a range of autoimmune disorders. In this report, we described a case study of a patient admitted to our Internal Medicine Department for a bone marrow biopsy and myelogram due to a monoclonal peak observed by his general practitioner. However, at admission he presented typical giant cell arteritis (GCA) complaints, suggesting the coexistence of both diseases. The possible pathogenesis, as found in the literature, explaining the association will be discussed. LEARNING POINTS: A relationship between AID and lymphoproliferative diseases, although rare, may occur and some studies suggest that the diagnosis of autoimmune disease has a negative impact on survival in MM patients. Bone marrow plasmacytosis can present a diagnostic dilemma, since it may be due to neoplastic or non-neoplastic conditions (that is, reactive plasmacytosis associated with AID, chronic infection, metastatic carcinoma, liver diseases and acquired immunodeficiency). Immunophenotyping in a myelogram or immunohistochemistry in bone marrow studies are useful in confirming a monoclonal plasma cell proliferation.