Giant mammary hamartoma diagnosed by stereomicroscopic analysis of the mammary glandular tree in an adolescent girl: Report of a case

This report describes a rare case of a giant hamartoma that developed in th e right breast of a 17-year-old girl. No abnormalities were found by endocr inological studies and a well-circumscribed tumor, approximately 20 cm in d iameter, was easily enucleated without bleeding during surgery, following w hich the bilateral breasts became nearly symmetrical. Histologic features r evealed predominant fibrous stroma and scattered normal or occasionally dys plastic mammary glands without neoplastic properties. No distorted lobular structures indicating fibroadenoma characteristics were observed. Subgross and stereomicroscopic analysis of serial 2-mm-thick sections revealed matur e normal lobules and predominant fibrous interstitial components. Therefore , the tumor was diagnosed as a giant hamartoma of the breast, according to the histologically non-neoplastic features and the delimited macroscopic ap pearance. This is a rare mammary gland disease characterized by the fact th at although each of the histological components seemed to be normal, their constitution was abnormal. It appears that not only histological features b ut also clinical details are indispensable for the diagnosis of this diseas e.