Ki-1-positive anaplastic large cell lymphoma initially diagnosed as Hodgkin's disease by fine needle aspiration (FNA) cytology

A 45-year-old male presented with a large mass in the left axilla. FNA cytology was interpreted as Hodgkin's disease (HD), lymphocyte depletion (LD) type, but histopathologic and immunohistochemical examination showed features of Ki-1-positive anaplastic large cell lymphoma. Unrepresentative sampling by the FNA from the tumour periphery resulted in a false impression of dual reactive and neoplastic cell populations. which together with the frequent Reed-Sternberg-like cells led to the initial erroneous impression of HD. Therefore, the cytologic diagnosis of HD, LD should be approached with caution.