Multiple myeloma to chronic lymphocytic leukemia: Transformation or co-occurrence? A case report

Multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) are malignancies of the elderly. While both these malignancies share the same lineage, their coexistence either simultaneously or subsequently is very rare. This report illustrates the case of an elderly female who was diagnosed with MM and received nine cycles of induction followed by maintenance for 2 years, but was lost to follow-up during the COVID-19 pandemic. After a 4-year hiatus as she represented, baseline evaluation was suggestive of disease remission, and therefore her maintenance therapy was resumed. However, after an eventful 7 months, the patient developed progressive lymphocytosis, which, on further evaluation, turned out to be CLL. There is a possibility that disease for more than one clone existed at baseline, but the patient was only symptomatic with one initially or it could be a myeloma-related secondary malignancy. This case prompts further evaluation of the pathophysiology and mechanism of such transitions.