Cytological diagnosis of primary cardiac diffuse large B cell lymphoma.

Sir,

We report the case of a 60-year-old immunocompetent man with no past medical history who was referred to cardiology department complaining of dyspnea. Chest radiography showed cardiomegaly and bilateral pleural effusions. Transthoracic echocardiography revealed a 51 × 50 mm mass occupying the right ventricle, extending to the tricuspid valve. Computed tomography scan showed an intracardiac mass measuring 66 × 53 mm with enhancement after contrast injection and pericardial effusion. Patient was lost to follow-up and readmitted 20 days later. Transthoracic echocardiography demonstrated pericardial effusion of 35 mm with signs of tamponade. He underwent urgent pericardial drainage which returned 600 cm3 of hemorrhagic fluid. Cell blocks were prepared from the effusion fluid specimen. Cytological examination of the pericardial fluid revealed hypercellular material with monotonous medium to large sized round cells mostly dispersed. Cells showed scant cytoplasm; nuclei were rounded with open chromatin and sometimes small nucleoli [Figure 1a]. The background showed scattered mesothelial cells. The initial cytological impression was large cell lymphoma. On immunocytochemistry tumor cells were strongly and diffusely positive for CD20 [Figure 1b]. Neoplastic cells were negative for CD3, keratin and calretinin. The diagnosis of effusion fluid involved by diffuse large B cell lymphoma was considered. An emergency thoracotomy was performed. The tumor had infiltrated the right atrium, the atrioventricular septum and the right ventricle. Surgical resection of the mass was incomplete. Histological exam confirmed the cytological diagnosis of diffuse large B cell lymphoma.

Figure 1

(a) Pericardial fluid on cell block: large atypical cells with round to irregular nuclear contours, coarsely clumped chromatin and inconspicuous nucleoli. The background showed scattered inflammatory cells (H and E, ×400). (b) Immunocytochemical study on cell block: diffuse and intense staining of neoplastic cells with CD20 (IHC, ×400)

Primary cardiac lymphoma (PCL) is defined as an extranodal lymphoma exclusively or mainly located in the heart and/or pericardium. PCL account for only 1.3% of all cardiac tumors and for less than 1% of extranodal lymphoma.[1] PCL is rapidly evolutive and is considered as an oncologic emergency.[2] This justifies rapid diagnostic procedure in the presence of clinical and radiological suspicion. Pericardial effusion is present in 58% of PCL. It's drainage can have both palliative and diagnosis purposes.[2-4] In the review of Ceresoli et al.,[2] cytological diagnosis of PLC is obtained in only 67%. The review of Ikeda et al.,[3] shows, that only 8 from 39 cases were diagnosed based on cytological examination of pericardial effusion. Cytological features include atypical lymphoid cells, monomorphic population of large cells or dissociated small round cells. The differential diagnosis includes benign reactive lymphocytosis and other neoplasms. Immunocytochemical staining is primordial to confirm the lymphoid lineage. Cytogenetic analysis and polymerase chain reaction can also be performed.[2] In the review of Petrich et al.,[5] the most common lymphoma subtype was diffuse large B-cell lymphoma (DLBCL), with 113 reports. Other reported subtypes constituted fewer than 10% each (Burkitt, T-cell lymphoma, small lymphocytic lymphoma, and plasmablastic lymphoma). Treatment options includes surgery, chemotherapy and/or radiation.[5] The overall response rate is 59% and the median over all survival is approximately 12 months.[5]

Primary cytological diagnosis of lymphoma in pericardial effusions is possible once the diagnosis is considered. Awareness amongst cytopathologists, that pericardial effusion can be the first manifestation of lymphoma should initiate the correct differential diagnosis and the use of confirmatory ancillary studies.