Coexistence of Essential Thrombocythemia and Waldenström Macroglobulinemia: A Case Report.

Waldenström macroglobulinemia (WM) and essential thrombocythemia (ET) are distinct hematologic malignancies that have only been reported to co-occur in one previous patient. We present a 64-year-old man with a significant family history for WM who was found to have both ET and WM. He had symptomatic ET, diagnosed by elevated platelets and a positive JAK2 V617F mutation, and asymptomatic WM was found on serum electrophoresis done for screening due to family history. Genomic evaluation of the myeloid and lymphoid cells suggested independent neoplastic transformation. This is the second reported case of a patient with both WM and ET. There was no evidence for a shared mechanism in these dual malignancies.