Fine-needle aspiration cytology of blastic natural killer-cell lymphoma (CD4+ CD56+ hematodermic neoplasm).

We describe fine-needle aspiration (FNA) cytology findings of a case of blastic natural killer (NK)-cell lymphoma. The patient was a 68-year-old man who was diagnosed with cutaneous blastic NK-cell lymphoma involving his forehead. He developed a 1.5 cm, right pre-auricular lymph node five months later. FNA cytology revealed a monomorphic population of medium-sized lymphoid cells with a dispersed single cell arrangement. The tumor cells contained eccentrically located nuclei with a plasmacytoloid appearance and moderate amount of grayish cytoplasm without azurophilic granules. The nuclei were round to oval with fine chromatin, small indistinct nucleoli, and frequent nuclear indentation. Many cells also showed elongated cytoplasm with a unique hand-mirror or ping-pong paddle-like appearance. The flow cytometry study obtained during the FNA revealed co-expression of CD4 and CD56 in the tumor cells that confirm the recurrence of a blastic NK-cell lymphoma to the pre-auricular lymph node. Copyright 2004 Wiley-Liss, Inc.