Hematolymphoid neoplasms in effusion cytology

Hematolymphoid neoplasms (HLNs) presenting as body cavity effusions are not a common finding. They may be the first manifestation of the disease. A diagnosis on effusion cytology may provide an early breakthrough for effective clinical management.

Study the cytomorphology of HLNs in effusion cytology, determine common types, sites involved and uncover useful cytomorphologic clues to subclassify them.

Twenty-four biopsy-proven HLN cases with malignant body cavity effusions and 8 cases suspicious for HLN on cytology but negative on biopsy are included in this study. Effusion cytology smears were reviewed for cytomorphological features: cellularity, cell size, nuclear features, accompanying cells, karyorrhexis, and mitoses.

Diffuse large B-cell lymphoma (37%) was the most common lymphoma type presenting as effusion followed by peripheral T-cell lymphoma (25%). Pleural effusion (75%) was most frequent presentation followed by peritoneal effusion (20.8%). Pericardial effusion was rare (4.1%). The common cytologic features of HLNs in effusions: high cellularity, lymphoid looking cells with nuclear enlargement, dyscohesive nature, and accompanying small lymphocytes. Mitosis and karyorrhexis were higher in high-grade HLNs when compared to low-grade HLNs. Myelomatous effusion showed plasmacytoid cells. Very large, blastoid looking cells with folded nuclei, high N: C ratio, and prominent nucleoli were seen in leukemic effusion.

HLNs have characteristic cytomorphology and an attempt to subclassify them should be made on effusion cytology. Reactive lymphocyte-rich effusions cannot be distinguished from low-grade lymphomas based on cytomorphology alone. Ancillary tests such as immunocytochemistry, flow cytometry, and/or molecular techniques may prove more useful in this regard.