Secondary B-cell acute lymphoblastic leukaemia in a patient with multiple myeloma

Although patients with multiple myeloma (MM) have improved survival with current therapies, there remains a long-term risk of treatment-associated second primary malignancies. We present a case of a patient with IgG kappa MM undergoing treatment for relapsed disease who was noted to have progressive pancytopenia. For his MM, he had previously undergone autologous stem cell transplant with high-dose melphalan and had received immunomodulatory (IMiD) agents in induction, maintenance and relapse regimens. A peripheral blood smear showed abnormal lymphoid cells, and a bone marrow biopsy revealed B-cell acute lymphoblastic leukaemia (B-ALL). He underwent intensive induction chemotherapy with plans for possible allogeneic stem cell transplant. Secondary B-ALL is a rare occurrence in patients with MM, with exposure to alkylating and IMiD agents being potential risk factors.