A rare case of concurrent JAK2V617F-positive essential thrombocythemia, multiple myeloma, and colorectal adenocarcinoma

Multiple myeloma (MM), essential thrombocythemia (ET), and colorectal adenocarcinoma (CA) are three distinct diseases. The co-occurrence of MM, ET, and CA in a single patient is exceedingly rare. Our study presents a remarkable case involving a 75-year-old patient who was simultaneously diagnosed with these three diseases. The JAK2V617F mutation was detected in the bone marrow with a variant allele frequency (VAF) of 13.38%, whereas the isolated CD138-positive plasma cells exhibited a significantly lower VAF of 0.38%. This notable difference implies the potential for separate origins of MM and ET. Additionally, the patient responded well to a bortezomib-based treatment regimen, despite the absence of specific therapy for ET. We believe that our findings add new understanding to these rare diseases and encourage further research in this area.