Solitary extramedullary plasmacytoma in the hilar region: A case of minimal marrow involvement in an elderly male.

Introduction And Importance: Solitary extramedullary plasmacytoma (SEP) is a rare plasma cell neoplasm, constituting around 3 % of plasma cell malignancies. SEP typically presents as a single tumor, either in bone or soft tissue, without systemic disease, and is often misdiagnosed due to its nonspecific symptoms. Diagnosis requires biopsy and extensive imaging studies to exclude multiple myeloma and other malignancies. Here, we present a case of SEP located in the hilar region, initially suspected to be a lung malignancy.

Case Presentation: A 70-year-old male with a history of hepatitis C presented with hemoptysis and shortness of breath. PET-CT revealed a metabolically active mass in the left hilar region, encasing major vascular structures and obstructing the left upper lobe bronchus, suggesting a neoplastic process. Transbronchial biopsy showed lymphoproliferative disease, and immunohistochemistry revealed monoclonal plasma cells, confirming SEP. Laboratory tests indicated mild monoclonal gammopathy, and bone marrow aspirate showed minimal involvement with plasma cells. A diagnosis of SEP with minimal marrow involvement was made.

Clinical Discussion: Extramedullary plasmacytomas are typically found in the head and neck, but rarer cases, like this one in the hilar region, may mimic lung cancer. A comprehensive diagnostic approach, including imaging, biopsy, and bone marrow analysis, is essential for accurate diagnosis and management.

Conclusion: This case underscores the importance of a multidisciplinary approach in diagnosing SEP, which can be easily confused with lung malignancy. Early detection and treatment, including surgery and radiotherapy, lead to favorable outcomes and reduced recurrence rates.