Breast hamartoma: fine-needle aspiration cytologic finding

Breast hamartoma is an unusual, well-circumscribed, tumor-like mass entering into the differential diagnosis of benign breast disease. To the authors' knowledge, the cytology of these lesions has not been well described. Although fine-needle aspiration is a well established procedure for the detection of breast carcinoma, its utility in classifying benign breast disease is less clear.

Fine-needle aspirates from eight patients with histologically proven hamartomas were reviewed. None of the cases had a preoperative fine-needle aspiration diagnosis of hamartoma. Cytologic characteristics were retrospectively evaluated in a semiquantitative manner and compared with the histologic findings.

The aspirates were moderately cellular and contained sheets of both bland ductal cells and lobular units. Adipose tissue was present in varying amounts. Bipolar stromal nuclei were readily apparent, whereas intact stromal fragments were less prominent. Cytologic atypia was uniformly absent.

The cytology of breast hamartomas shows considerable overlap with other benign breast disease and is unlikely to be interpreted as malignant. The findings of intact lobular units and a relative paucity of stroma in an aspirate from a well circumscribed breast lesion may suggest the diagnosis of hamartoma.