Intramammary granular cell myoblastoma.

Two female patients, age 15 and 21 years, with intramammary granular cell myoblastoma who were without recurrence of the development of additional lesions after one year and eight years, nine months respectively, are reported. Electron microscopic examination of one of our cases disclosed the typical osomphilic granules but no features to support a particular cell of origin. Review of the 52 previously reported cases indicates that this unusual intramammary neoplasm has been encountered with relatively few exceptions in the 20 to 59 year age group and in the upper quadrants. It clinically mimics fibroadenoma or carcinoma and on frozen section examination may be misinterpreted as malignant. None have recurred following adequate excision.