Bone marrow trephine biopsy findings in a case of myeloma with large immunoblast‐like cells

Abstract

The diagnosis of myeloma requires the presence of 10% or more clonal plasma cells on bone marrow examination or of a biopsy-proven plasmacytoma along with evidence of end-organ damage that can be attributed to the underlying plasma cell disorder [1]. The above-mentioned case had >90% neoplastic plasma cells in the bone marrow and a significant anaemia as a result of the bone marrow infiltration. Cytological features of myeloma cells can be highly variable. They include tumors with mature and benign appearing plasma cells; small lymphoid-like cells; atypical but differentiated plasmacytic cells; blastic cells with high nucleus: cytoplasmic ratio and fine chromatin; large cells with immunoblastic features and highly pleomorphic forms. The current case showed immunoblastic features and pleomorphism. Differential diagnosis varies as per the cytological features and includes benign/reactive plasma cell infiltrates, small cell lymphomas, large cell lymphomas, metastatic carcinomas, and other metastatic tumors. Documentation of the expression of immunoglobulin either at protein level or at RNA level confirms the B-cell/plasma cell lineage of these tumors. Expression of CD138, CD79a, and CD56 is helpful in the diagnosis of myeloma, though carcinomas can express CD138 and those with neuroendocrine features can express CD56. Expression of cyclin D1 is noted in 40% of cases and is a very helpful feature in the diagnosis and follow-up of myeloma on bone marrow trephine biopsies [2]. Cases with uniform and strong expression of cyclin D1 are associated CCND1 translocation. A man in his seventies presented with anemia, pyrexia, and chest symptoms. His hemoglobin was 7 g/dL and white cell count 7.7 3 10 9 /L, neutrophils 5.08 3 10 9 /L and platelets 87 3 10 9 /L. His globulin was 105 g/L, and further evaluation of serum proteins showed that he had an IgG Kappa paraprotein of 84 g/L. The urine revealed the presence of an IgG Kappa paraprotein of 5.3 g/L and presence of Bence-Jones protein. On the skeletal survey, there were no osteolytic lesions. Bone marrow aspirate revealed sheets of large abnormal cells with large nuclei and prominent nucleoli. The cytoplasm was basophilic with perinuclear halo (a-c; MGG, 31000). Bone marrow trephine biopsy showed hypercellular marrow (d; H&E, 3100), and was entirely replaced by sheets of atypical large cells with large nuclei having relatively fine chromatin and prominent nucleoli, which were often single and centrally located; they had moderate amounts of cytoplasm and the plasmacytic features with eccentric placement of nuclei being subtle (e; H&E, 3600). The neoplastic cells were positive for CD138 (f), CD56 (g) and a proportion of cells expressed cyclin D1 at variable intensities (h). In-situ hybridization for light chains showed kappa light chain restriction [kappa (i) and lambda (j)] (magnifications of e-j X400).