LAUSR

Dear Editor, A 68-year-old Caucasian male with a history of multiple myeloma (MM) IgA kappa with several right thoracic and paravertebral plasmacytomas attended the emergency room due to fever, dyspnoea and cough. Moderate amount of right pleural effusion (PE) was demonstrated by imaging. Serosanguineous pleural fluid was exudative, with negative microbiological tests. Cytomorphological assessment of the PE showed a 55% infiltration by plasma cells with plasmablastic features (Fig. 1a, b). Malignant plasma cell population at PE was demonstrated by flow cytometry analysis (Fig. 1c): CD38, CD138, CD56 (homogeneous), CD19, CD20, CD45, CD27, CD28, CD81, CD117, kappa restricted and high side scatter. After malignant PE (MPE) plasma cell purification, karyotype and FISH analysis were performed, demonstrating hyperploid and highly complex cellularity with several chromosomal markers (Fig. 1d) and 1q21 gain. Pleural fluid electrophoresis was not performed. Blood tests were normal, and abnormal serum protein electrophoresis and immunofixation were negative. Bone marrow assessment did not find MM infiltration. No plasmacytomas were found by PET. Histologic examination of the oral mucosa and pleural biopsies ruled out amyloid deposition. The patient was managed with PE drainage, pleurodesis by bleomycin instillation, local radiation and systemic therapy for MM (pomalidomide, cyclophosphamide and dexamethasone standard protocol every 28 days). After 3 months, symptoms and myelomatous PE had disappeared. Nine months later, the patient presented his second MPE episode, also managed with local and systemic treatment. The patient died 18 months after the first MPE episode; the cause of death was MM progression. Patients with MM occasionally present PE during follow-up; some causes are infections, renal failure, hypoalbuminemia, pulmonary embolism or heart failure due to amyloidosis. Effusion due to pleural myelomatous involvement is rare, occurring in less than 1% of cases [1]. Most cases are MM IgA type and occur in the left side of the chest [2]. MPE due to MM is related to pleural involvement secondary to extension of a chest wall plasmacytoma or an adjacent skeletal lesion, hematogenous spread, lymphatic obstruction or direct pleural infiltration of myeloma cells [3]. In our case the history of right thoracic and paravertebral plasmacytomas might have a role in the development of MPE. The diagnosis of myelomatous PE is difficult in some cases. Diagnosis can be reached by cytologic identification of malignant plasma cells in the pleural fluid, histologic assess of a pleural biopsy and/or demonstration of the monoclonal protein in pleural fluid electrophoresis [1, 2]. Cytological identification of atypical plasma cells within the PE has been considered as the best diagnostic method for malignant infiltration. The presence of very immature plasmocytes named plasmablasts is the most uncommon morphological pattern, observed in 10– 15% of myelomatous PE cases [4]. Flow cytometry and cytogenetics are not routinely performed, nor reported in literature. MPE due to MM implies a worse prognosis, with a 4-month overall median survival [3]. Therapeutic management is not standardized. PE drainage, pleurodesis, pleural catheter placement and/or local radiation should be considered, as well as systemic treatment for MM [2, 5]. * Fernando Martín-Moro [email protected]