Pitfalls in the Cytological Diagnosis of Nodal Hodgkin Lymphoma

Hodgkin lymphoma (HL) is a hematopoietic neoplasm characterized by malignant Reed-Sternberg (RS) cells in an inflammatory background. Although the cytological features of HL are well elucidated in literature, yet many postulated factors cause its misdiagnosis. This study aims to assess the diagnostic reliability of fine needle aspiration cytology (FNAC) in HL and evaluate the factors contributing to a false-negative and false-positive diagnosis, taking histopathology as the gold standard.

This was a retrospective study in which 47 cases of HL diagnosed on histopathology were compared with their prior cytological diagnosis.

The patient's age ranged from 3 to 80 years (median: 36 years) with a M:F ratio of 2.9:1. Lymph node aspirations were performed from multiple anatomical sites, out of which the cervical was the most common (57.8%). FNAC was inconclusive in two cases due to unsatisfactory smears. The false-negative diagnosis of reactive lymphadenitis was given in four cases, and false-positive in four cases, which included three cases of non-HL, and one case of malignant small round blue cell tumor. The overall diagnostic accuracy of FNAC in the diagnosis of HL was 82.2%.

The cytological diagnosis of HL can be challenging when classic RS cells are absent. Contributing factors for a false-negative diagnosis include obscuring reactive inflammatory cells, fibrosis of the involved lymph nodes, partial involvement of the lymph node, and misinterpretation. A thorough clinical examination with evaluation of FNAC smears from multiple areas, and ancillary tests help improve the diagnostic accuracy of cytological diagnosis.