Dual Diagnosis of Multiple Myeloma and T-cell Large Granular Lymphocytic Leukemia: A Case Report and Literature Review

A 52 year-old Caucasian male with stable Crohn’s disease off medications, with anemia and known vitamin B12 and iron deficiency, was noted to be pancytopenic with a white blood cell count of 1,600/uL and a platelet count of 106,000/uL. He also noted night sweats, fatigue, and a distended abdomen. While admitted with febrile neutropenia due to methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia in the setting of a rectal abscess, further workup revealed a new diagnosis of lambda light chain multiple myeloma (MM). After 4 cycles of chemotherapy, he achieved a partial response but remained cytopenic and developed increased splenomegaly. Extensive workup resulted in the diagnosis of T-cell large granular lymphocytic leukemia (T-LGLL) by T-cell receptor gene rearrangement studies. Initiation of oral cyclophosphamide with corticosteroids resulted in improvement in blood counts, and he was consolidated with an allogeneic stem cell transplant. His MM appeared to be in a stringent complete remission at 30 months, whereas the T cell rearrangement for T-LGLL was initially negative but then became positive again 7 months later. T –LGLL is a clonal disease of large granular lymphocytes, typically cytotoxic T cells, which accounts for 2-3% of all cases of chronic lymphoproliferative disorders. Common symptoms include fever, recurrent bacterial infections, weight loss, and fatigue. Labs usually note cytopenias, and both splenic and hepatic involvement are common. T-LGLL is often associated with autoimmune disorders, and may co-exist with other hematologic malignancies, seldomly with a primary diagnosis of multiple myeloma (MM). Given the rarity of the disease and its typically indolent course, there are no standard treatment guidelines, and immunosuppressive chemotherapy is reserved for cases of symptomatic cytopenias and splenomegaly. In an era with increasing concerns about secondary malignancies in MM, the differential for patients with persistent cytopenias and/or splenomegaly despite treatment should include concomitant T-LGLL.