The utility of chest ultrasound-guided fine-needle biopsy in the diagnosis of plasmacytoma

BACKGROUND: Plasmacytoma is a plasma cell dyscrasia originating from a single clone of plasma cells of B-lymphocyte lineage and produces a monoclonal immunoglobulin. Transthoracic fine-needle aspiration (TTNA) under ultrasound (US) guidance is a well-validated technique for the diagnosis of many neoplasms and has been shown to be safe and cost effective, with diagnostic yields comparable to more invasive techniques. However, the role of TTNA in the diagnosis of thoracic plasmacytoma is not well established. OBJECTIVES: The aim of this study was to assess the utility of TTNA and cytology in confirming a diagnosis of plasmacytoma. METHODS: All cases of plasmacytoma diagnosed from January 2006 to December 2017 by the Division of Pulmonology, Tygerberg Hospital, were retrospectively identified. All patients who underwent an US-guided TTNA and of whose clinical records could be retrieved were included in this cohort. The International Myeloma Working Group’s definition of a plasmacytoma was used as the gold standard. RESULTS: A total of 12 cases of plasmacytoma were identified and 11 patients included (one patient was excluded owing to missing medical records). Six of the 11 patients (mean age 59.5 ± 8.5 years) were male. Radiologically, most had multiple lesions (n=7), most commonly bony (n=6) with vertebral body involvement (n=5) and pleural-based lesions (n=2). Rapid onsite evaluation (ROSE) was performed and documented in 6 of the 11 cases, and a provisional diagnosis of plasmacytoma was suggested in 5 of the 6 patients (83.3%). The final laboratory cytological diagnoses of all 11 cases were compatible with plasmacytoma which was further confirmed via a bone marrow biopsy (n=4) and by serum electrophoresis (n=7). CONCLUSION: US-guided fine-needle aspiration is feasible and is useful to confirm a diagnosis of plasmacytoma. Its minimally invasive nature may be the ideal investigation of choice in suspected cases.