Solitary extramedullary plasmacytoma of the lung with rapid transition to multiple myeloma : A rare case report and brief literature review.

Introduction: Solitary extramedullary plasmacytomas (SEPs) are disease entities characterized by the local proliferation of neoplastic plasma cells, representing less than 6% of plasma cell tumors. They typically produce monoclonal immunoglobulin and are usually found in the head, neck, and, less commonly, in the lungs. SEP, in rare instances, can transition to multiple myeloma (MM) with an estimated risk between 8 and 31%.

Case presentation: We report the case of a 72-year-old woman who sought medical attention at the emergency department due to acute onset dyspnea and syncope. Laboratory results revealed elevated creatinine, hypercalcemia, and anemia, all of which were absent at a hospitalization three months prior for tuberculosis. A chest x-ray showed a right upper lobe opacity, and a computed tomography (CT) scan demonstrated an apical lung mass with calcifications. A CT-guided needle aspiration of the mass indicated SEP. Bone marrow biopsy subsequently confirmed MM. The patient was admitted to the intensive care unit and treated with chemotherapy; however, following a complicated hospital course, she died.

Discussion: SEPs are an exceedingly rare form of malignancy with the potential for conversion to MM. Although the likelihood of transformation to MM in months is rare, we call for attention to the possibility of such transition and the clinical prognosis of patients with SEP. Prompt and aggressive treatment is essential, and this, to our knowledge, is the first case of conversion to MM in less than four months following the initial diagnosis of SEP of the lung.