Benign spindle and inflammatory lesions of the breast: diagnosis by fine-needle aspiration

We describe fine-needle aspiration (FNA) findings in 7 patients with breast masses showing numerous spindle cells in smear material. The benign nature of these lesions was confirmed by clinical follow-up (n = 4) or surgical excision with histologic examination (n = 3). The final diagnosis included one case each of myofibroblastoma, juvenile hypertrophy, post-FNA reactive stromal proliferation, stromal induction in proliferative fibrocystic disease, and subareolar abscess. There were two instances of granulation tissue. The case of stromal induction was initially felt to be suspicious for phyllodes tumor. The post-FNA stromal reaction was considered sufficiently atypical to warrant histologic investigation. The importance of historical and physical examination findings in accurate interpretation of these uncommon cases is emphasized. Some will require histologic assessment for final diagnosis.