CD38 negative anaplastic plasma cell myeloma with (14;16) translocation: a diagnostic dilemma for highly aggressive neoplasm: case report

Anaplastic plasma cell myeloma (PCM) is an aggressive morphological variant of myeloma characterized by involvement of extramedullary sites and extremely poor prognosis. Moreover, anaplastic PCM is frequently associated with high frequency of 17p(p53) deletions, 1q21(CKS1B) amplifications and immunoglobulin A (IgA) isotype. It usually manifests as an adverse progression of previously treated conventional plasma cell myeloma. However, the anaplastic morphology can be encountered in newly diagnosed cases and might pose a major diagnostic challenge. Herein, we present a rare case of anaplastic plasma cell myeloma with (14;16) translocation which was diagnosed initially as a non-hematopoietic malignancies due to its unusual clinicopathological profile comprising acute presentation, extremely anaplastic morphology, and negative staining of CD38 immunohistochemical marker. In view of lack of clinical suspicion of plasma cell myeloma, no serological investigations for myeloma had been requested initially. In fact, high index of suspicion of myeloma arose only when results of MRI and CT scan came out revealing bony lytic lesions and collapsed vertebrae. Subsequently, bone marrow biopsy was repeated and revealed an extensive infiltration with sheets of neoplastic plasma cells which were strongly positive for CD138, KAPPA, and CD56 IHC markers.