Mammary epidermoid inclusion cysts after wide-core needle biopsies.

AIMS: To investigate the prevalence of squamous epidermoid inclusion cysts after wide-core needle biopsy. METHODS AND RESULTS: Epidermoid inclusion cysts were found in five of 17 surgical excisions (29%) after preliminary wide-core needle biopsies in a 7-month period. Thereafter they were not seen in 26 subsequent postwide-core surgical excisions in a period of 6 months. CONCLUSIONS: The cysts appear to be an iatrogenic complication of wide-core biopsy, and need morphological recognition in order to avoid confusion with spontaneous squamous metaplasia of benign or malignant breast epithelium. Longer term implications are unknown.