Concurrent Invasive Carcinoma and Fibroadenoma Arising from Bilateral Ectopic Breast Tissue in the Chest Wall: A Case Report and Literature Review.

Ectopic breast tissue, which results from incomplete regression of the mammary line during embryogenesis, is observed in 0.2%-6% of the population. Carcinoma development in ectopic breast tissue, especially in the abdominal or chest wall, is rare. Here we present the unusual case of a 38-year-old woman with invasive ductal carcinoma in the ectopic breast tissue on the left side of the chest wall and concurrent fibroadenoma in the ectopic breast tissue on the right side. We also describe the US and MR findings of these masses.