Plasmablastic Myeloma versus Plasmablastic Lymphoma: Different Yet Related Diseases

Abstract

We describe a case of ileal plasmablastic myeloma in a 77-year-old otherwise immunocompetent male patient. The patient presented with weight loss, abdominal pain, and loose stools. Imaging studies demonstrated wall thickening in the distal ileal loop. He underwent ileocolectomy and pathology was consistent with plasmablastic neoplasm. Subsequently, the pathologic evaluation was felt to be consistent with a small bowel plasmablastic myeloma that was EBV positive, C-MYC negative, CD56 and CD138 positive, Ki-67 score greater than 90%, and lambda light chain mRNA restricted. Plasmablastic myeloma is a rare and aggressive neoplasm with a poor prognosis. Similarly, plasmablastic lymphoma is also a rare, aggressive, and typically fatal disease that is often associated with HIV. Both PBL and PBM have several overlapping cytomorphologic and immunophenotypic features, making a precise diagnosis difficult to provide to patients. Immunophenotypically, CD38 and CD138 positivity is unreliable to differentiate between PBL and PBM. Plasmablastic myeloma tends to have worse outcomes than other plasma cell dyscrasias. Moreover, there is very limited data on plasmablastic myeloma of the small bowel and treatment recommendations are based solely upon antidotal experience. Molecularly, there is information that plasmablastic myelomas and lymphomas are related neoplasms, which indicates that there may be treatment overlap between these two neoplasms.