Anaplastic Multiple Myeloma: Case Series and Literature Review

Anaplastic multiple myeloma (AMM) is a very rare but distinct subtype of multiple myeloma (MM) with an extremely poor prognosis. Due to its rarity, AMM lacks detailed descriptions and clear definitions. Moreover, there is no consensus on the treatment and evidence suggests that AMM responds poorly to several novel therapies. We conducted a literature review and retrospective case series to determine clinical characteristics, pathological features, and outcomes of AMM.

Published case reports and case series of AMM since 1983 were systematically extracted and reviewed. A total of 52 patients with AMM were reported in the PUBMED since 1983, including 26 males (50%) and 26 females (50%). The age ranged from 29 years old to 85 years old, with a mean age of 57.02 years old. Most of the patients presented with bone pain (23, 44.2%), fatigue (18, 34.6%), plasmacytoma (18, 34.6%) and weight loss (7, 13.5%). The median survival of the patients was 4 months. To investigate the outcomes of patients with AMM in the current era of treatment, a series of 14 patients with AMM diagnosed at our institute between December 2012 and July 2021was retrospectively analyzed. Our retrospective case series consisted of 12 males (85.7%) and 2 females (14.3%), with a mean age of 59 years old. Most of our AMM patients displayed bone lytic lesions as a common manifestation. The common cytogenetic abnormality was 1q amplification. All patients received standard combination chemotherapy consisting of proteasome inhibitors and/or immunomodulatory agents, and half of the patients underwent autologous hematopoietic stem cell transplantation. The median progression-free survival (PFS) and overall survival (OS) for our 14 AMM patients were 0.84 years and 1.52 years, respectively, which was significantly worse than the regular MM patients treated at our institute from 2003-2013 who had a PFS of 2.28 years and OS of 4.92 years.

AMM is a very rare, morphologically distinct variant of MM. It has adverse cytogenetics and an aggressive course. It is often resistant to standard chemotherapy and presents with an extremely low survival rate.