Nodular sclerosis classical Hodgkin lymphoma grade 2: A diagnostic challenge to the cytopathologists

BACKGROUND: Grade 2 nodular sclerosis classical Hodgkin lymphoma (NSCHL) is less common than grade 1 lymphoma and has a worse overall prognosis. To the best of the authors' knowledge, no study of a large series of cases has been performed until now. The objective of this study was to assess the diagnostic efficacy of cytology for grade 2 NSCHL versus grade 1 NSCHL and study the morphological features of grade 2 NSCHL in fine-needle aspiration cytology (FNAC). METHODS: Fifteen of 51 histopathology-proven cases of NSCHL (18 FNAC procedures) were grade 2, and 36 were grade 1. The efficacy of FNAC for detecting grade 1 and 2 NSCHL was assessed, and the frequency of misdiagnosis was compared. The clinical details and cytomorphological features of grade 2 NSCHL were studied in detail. RESULTS: Among the grade 1 NSCHL patients, 58.4% were diagnosed with Hodgkin lymphoma (HL) or had findings suggestive of HL, whereas 20% of the grade 2 patients were diagnosed HL or suggestive of HL. Two cases of grade 2 NSCHL were misdiagnosed as anaplastic large cell lymphoma, and 4 were misdiagnosed as malignant neoplasms. Grade 2 NSCHL cases showed clusters and sheets of mononuclear, multinucleated, and bizarre cells, with some cases showing a suppurative background. However, extensive searching showed occasional Reed-Sternberg (RS) cells in most of the cases, and lacunar cells were seen in 12 cases. CONCLUSIONS: The diagnostic efficacy of FNAC is much lower for grade 2 NSCHL versus grade 1 NSCHL. The search for an occasional RS cell and the identification of lacunar cells can provide a clue for the diagnosis. Cancer Cytopathol 2017;125:104-113.