(1129) Respiratory Compromise Secondary to a Solitary Plasmacytoma: A Case Presentation

Introduction: Solitary Plasmacytoma (SP) is a rare plasma cell dyscrasia that occurs in bony or soft tissue. In multiple myeloma (MM), SP may develop as a localized manifestation of the disease (4). SP are classified into 2 subtypes: solitary plasmacytoma of bone (SPB), and extramedullary plasmacytoma (EP), which occurs in soft tissues. SP are more common in males , and can occur anywhere and present without any evidence of systemic disease (1). The cumulative incidence is 0.15/100,000 (3). SP can rarely progress to multiple myeloma (MM) with a median time of progression of 2-3 years. The following vignette will present a case of airway compromise due to a posterior mediastinal SP.

Description: A 76-year-old female with past medical history of stage II IgG MM presented with shortness of breath. Computed tomography (CT) chest revealed severe narrowing of the trachea from mass effect, and a new extensive mediastinal mass since a prior positron emission tomography (PET/CT) 3 months prior. The patient underwent endobronchial ultrasound (EBUS) with biopsy and was intubated. Biopsy revealed plasma cell neoplasm, consistent with SP. She was treated with radiation therapy to decrease tumor burden to facilitate extubation. She was not a surgical candidate due to the high risk location of the mass. After poor response to radiation therapy, comfort care was pursued and the patient expired shortly after extubation.

Discussion: This rare presentation highlights the locally invasive characteristics of SP without signs of systemic disease, and demonstrated the rapid proliferation of SP highlighted by her normal PET 3 months prior. The presence of SP in the posterior mediastinum can cause severe complications due to its proximity to structures in the mediastinum. Diagnosis is confirmed with presence of monoclonal plasma cells on biopsy, and imaging is required to evaluate for soft tissue or bone lesions. Treatment includes radiation and surgery. While locally invasive, SP are highly sensitive to radiation (2). Surgical resection is effective, but tumor excision without subsequent radiotherapy results in a high rate of recurrence (2). In patients with history of MM presenting with respiratory failure and concern for airway obstruction, this case emphasizes consideration of plasmacytoma on the differential.