P2.04-047 A Rare Case of Extramedullary Plasmacytoma Occurring in the Posterior Mediastinum: Topic: Esophageal Cancer and Other Malignancies

Abstract

Extramedullary plasmacytoma (EMP) is a rare neoplasm that is derived from a monoclonal proliferation of plasma cells in the soft tissues or organs outside the bone marrow and is present in about 3% of all plasma cell neoplasms. The average age of patients is about 60 years. The most frequent site is the upper respiratory tract (approximately 80%). The endotoracic forms usually manifest as nodules or pulmonary masses. Rarely may it present with mediastinal mass as a primitive solitary lesion. We present a case of extramedullary plasmacytoma of the posterior mediastinum. A 82 years old female presented to us with a history of chest pain, persistent cough, dysphagia, asthenia and dyspnea for few weeks. She denied smoking and had ischemic heart disease and atrial fibrillation as comorbidities. Her serum protein electrophoresis and hemocythometric parameters were normal. Chest X-ray showed a posterior voluminous endothoracic opacity and chest Computed Tomography showed an expansive hypodense lesion of the posterior mediastinum of 15.6 × 9.1 cm, which surround and displaced the thoracic aorta causing compression of the esophagus and central airways without pathological lesions of the lung parenchyma and the presence of a modest bilateral pleural effusions. Transbronchial needle aspiration under eco-endoscopic guide (EBUS-TBNA) has revealed the presence of isolated elements plasma cell-like (CD138+, lambda chains+). For a precise (correct) histological definition we performed a surgical biopsy of the mediastinal mass through right uniportal video-assisted thoracoscopic surgery (VATS). Pathological examination revealed solid tissue with massive infiltration of elements plasma cell-like. Immunohistochemical analysis showed positive staining for CD138 (plasma cell marker), CD56 (pathological plasma cells marker), monoclonal light chains lambda and negative for CD3 (marker of T line lymphoproliferative diseases). Therefore, a final diagnosis of extramedullary plasmacytoma was made. Our case of EMP without systemic signs of multiple myeloma is extremely rare, especially like a mediastinal mass as a primitive solitary lesion. In terms of posterior mediastinal manifestations of EMP, it should be differentiated from neurogenic tumor, lymphoma, and lymphangioma. 1 EMP could be concurrent with multiple myeloma or the sequences of proceedings for multiple myeloma, the prognosis is very poor and worse than primitive forms. Therefore, precise and timely framing (classification) of the disease is essential for diagnostic and therapeutic purposes.