Renal and Extramedullary Involvement Revealing Atypical Multiple Myeloma: A Case Report and a Literature Review.

BACKGROUND

Multiple myeloma (MM) is a plasma cell malignancy with diverse clinical manifestations. Beyond the classic CRAB features (hypercalcemia, renal insufficiency, anemia, and lytic bone lesions), extramedullary involvement is rare and often life-threatening. This case highlighted atypical and severe pulmonary-pleural manifestations, emphasizing the diagnostic complexity of extramedullary disease.

CASE PRESENTATION: A 67-year-old hypertensive man was admitted with fever, dyspnea, and hemoptysis. He presented with pleural effusion, biologically confirmed alveolar hemorrhage, nephrotic-range proteinuria, and osteolytic lesions. Cytology demonstrated pleural plasmacytic infiltration, and bone marrow aspiration showed 100% plasmacytosis. He was diagnosed with immunoglobulin G-kappa MM with pulmonary and pleural extramedullary disease and achieved partial remission with melphalan-dexamethasone, maintaining clinical improvement for 12 months.

CONCLUSION

This case illustrated rare, severe extramedullary manifestations of MM with renal dysfunction as a key clinical clue. It underscored the importance of early recognition and comprehensive diagnostic evaluation. Prognosis remains poor in aggressive variants despite timely treatment.