Myofibroblastoma is an uncommon neoplasm of the male breast. Herein, we describe the cytologic features seen in the fine-needle aspirate of a 45-year-old man. The smears were cellular with intimate association of tumor cells with extracellular matrix material. The cells were spindle to polygonal and were without significant atypia. Numerous mast cells were observed. Nuclear grooving was present only occasionally, although this was conspicuous histologically. The presence of hyaline bands in between tumor cells, another interesting feature, was appreciated retrospectively. This neoplasm was initially misinterpreted as a malignant soft tissue tumor. Awareness of the cytologic features coupled with mammography should prevent a misdiagnosis of this tumor.

Copyright 2002 Wiley-Liss, Inc.