Concomitant plasma cell myeloma and chronic myelomonocytic leukemia in elderly: diagnostic complexity, therapeutic challenges - case report and literature review.

Introduction and importance: Chronic Myelomonocytic Leukemia (CMML) is a rare clonal hematopoietic disorder with overlapping features of myelodysplastic syndromes and myeloproliferative neoplasms. Its diagnosis becomes more challenging when coexisting with other hematologic malignancies. We report a rare dual pathology of CMML and plasma cell myeloma in an elderly female, highlighting the complexity of diagnosis and management. Case presentation: An 82-year-old female, previously treated for cervical cancer, presented with bilateral buttock pain, gait disturbance, and weakness. Laboratory findings revealed marked leukocytosis (WBC 85 × 10 Clinical discussion: This case illustrates the diagnostic complexity of overlapping hematologic malignancies. The coexistence of CMML and myeloma, although rare, was confirmed through integrated morphologic, immunophenotypic, and molecular analysis. The presence of NRAS and TET2 mutations supported CMML. Treatment required balancing cytoreduction with supportive care, especially given her renal dysfunction and marrow suppression. Conclusion: Dual hematologic malignancies demand a multidisciplinary approach. In elderly patients with cytopenias and monocytosis, thorough diagnostic workup is crucial. This case emphasizes the need for personalized therapy in complex hematologic overlap syndromes.