Fine needle aspiration of myofibroblastoma of the breast in a man. A report of two cases.

The cytopathologic features of fine needle aspiration biopsy of two myofibroblastomas of the breast in men are described. The cytologic findings consisted of monomorphic spindle cells with ovoid, grooved nuclei, isolated or in clusters, with an ill-defined, short fascicular pattern and abundant acellular, myxoid-appearing material. Atypical features were absent. No epithelial elements were present. We emphasize the value of aspiration cytology in association with clinical and mammographic data to establish a definitive diagnosis of this uncommon entity. This benign tumor should be considered in pure spindle cell, nontypical fine needle aspiration biopsy specimens of breast masses with sharp demarcation from the surrounding tissue, especially in men.