Introduction: The concomitant occurrence of myeloproliferative neoplasms (MPNs) and plasma cell dyscrasias is rare and presents significant diagnostic challenges. Accurate distinction between overlapping features is essential, particularly when bone marrow fibrosis (BMF) is present. Case Description: We report a 57-year-old female, with a 10-year history of thrombocytosis managed with antiplatelet therapy, who presented with anemia and severe lumbar pain. Bone marrow biopsy revealed marked fibrosis, and imaging revealed multiple vertebral lesions. Diagnostic workup identified features consistent with myelofibrosis (MF) and coexisting IgG-Kappa multiple myeloma (MM). Although the patient initially fulfilled WHO criteria for MF, the rapid resolution of fibrosis following first-line plasma-cell-directed therapy suggested a secondary, cytokine-mediated process rather than a true concomitant MPN. Conclusions: This case highlights the importance of an integrated diagnostic approach in patients with overlapping features of hematologic malignancies. Differentiating between MM-associated fibrosis and true concurrent MPN and MM is critical, as misclassification may alter both prognosis and therapeutic strategy. In triple-negative cases, the histologic response to plasma-cell-directed therapy can serve as a key discriminating criterion. Awareness of the potential association between MM with fibrosis and extramedullary disease is also essential for clinical management. This case underscores the importance of an integrated diagnostic approach in patients with overlapping hematologic features.
Fiallo-Suárez et al. (Sat,) studied this question.