Utility of fine-needle aspiration cytology combined with flow cytometry in extramedullary hematolymphoid lesions - A cross-sectional study.

Objective: Flow cytometry (FC) can be an adjunct to fine-needle aspiration cytology (FNAC) in the diagnosis and subclassification of hematolymphoid lesions. This study evaluates the utility of FC in diagnosing extramedullary hematolymphoid lesions in fine-needle aspirate samples.

Material and methods: This cross-sectional study enrolled patients who presented to the FNAC clinic and suspected to have hematolymphoid lesions (nodal and extra nodal lesions) from August 2020 to June 2022. Sixty-seven cases of hematolymphoid malignancies and 67 cases without hematolymphoid malignancies were included. The combined FNAC/FC diagnosis was compared with the gold standard: Biopsy, cell block, or peripheral blood/bone marrow aspirate FC.

Results: Of 67 lymphoma cases, 63 were of the primary type and 4 were diagnosed with suspected recurrence/residual disease. Moreover, 57 cases were nodal, and 10 were extranodal. Four of the patients had discordant findings between FNAC and FC. The gold standard was available only in 56 cases, of which 5 had discordant findings between combined FNAC/FC and the gold standard. We subclassified 34 cases based on combined FNAC/FC. The five cases included anaplastic large cell lymphoma (1/5), classic Hodgkin lymphoma (3/5), and one case of atypical lymphoid hyperplasia. Non-contributory FC was attributed to the presence of large cells/necrosis/nodular lymphocyte predominant Hodgkin lymphoma/metastasis/Castleman disease/technical problem.

Conclusion: Combining FC with FNAC enhances diagnostic accuracy and helps subclassify lymphoma. Future works should explore whether it can replace excision biopsy, especially in recurrent cases.