Fibroadenoma Arising in Axillary Ectopic Breast Tissue. A Diagnostic Challenge.

Ectopic or accessory breast tissue may occur in primitive embryonic milk lines or locations other than the milk line. The same pathology arising in breast tissue may occur less frequently in ectopic breast tissue. Fibroadenomas rarely occur in ectopic breast tissue, with less than 50 reported cases in the English literature, despite being the most common benign breast neoplasms. Diagnosing fibroadenoma in ectopic breast tissue can be challenging due to the lack of clinical suspicion and the atypical findings in imaging studies. Treatment consists of surgical excision. In this manuscript, we present a case of a 24-year-old patient with a fibroadenoma of the left axilla arising in bilateral axillary ectopic breast tissue, and we comprehensively review the literature.

Matrix-producing Breast Carcinoma: A Rare Subtype of Metaplastic Breast Carcinoma.

Matrix-producing carcinoma (MPC) is a rare subtype of metaplastic breast carcinoma (MBC) that was first described in 1989 by Wargotz and Norris. It accounts for less than 1% of breast carcinomas and has distinctive clinical, morphological, and immunohistochemical features. Histologically it consists of invasive carcinoma of no special type with transition to cartilaginous or osseous matrix without a spindle cell component. Data on this entity are limited with the literature consisting mostly of case reports and a small number of case series. We report a case of matrix-producing breast carcinoma, with excellent clinical outcome. We also discuss the histogenesis, imaging, histological, and immunohistochemical characteristics, treatment, and focus on the differential diagnosis of this rare tumor.