Plasma cell myeloma with tumorous liver involvement, presenting as a carcinoma of unknown primary

Abstract

Background: A hepatic tumor mass by plasma cell myeloma is rare and is reported in 16% of patients with plasma cell myeloma. Unusual morphological variants of plasma cell myeloma in such a localisation may be a diagnostic challenge. Case presentation: A 60-year-old woman with low-back pain had MRT and CT scan results showing osteo-destructive lesions on different sites and a tumor mass in the liver. Her clinical presentation was classified as a carcinoma of unknown primary. Elevated serum-levels of the immunoglobulin heavy chain IgA and the immunoglobulin light chain kappa gave rise for a bone marrow trephine biopsy, revealing infiltration by a plasma cell myeloma with typical morphology (Fig.1A). Though the histological specimen of the liver resembled a clear cell carcinoma, the immunophenotype revealed plasma cell myeloma. Conclusion: In tumours with an extraordinary morphology and not conclusive immunohistochemical results, the use of plasma cell antibodies may lead to the correct diagnosis.