Abstract
An 83-year-old woman was admitted to our hospital for evaluation of a right breast tumor. A hard and elastic tumor was palpable in the C area in the right breast. A high density mass with flat margins was detected in the mammographic findings. Histological findings obtained from a core needle biopsy suggested malignancy. The extirpated mass, 2.8 cm in size, did not show any signs of malignancy and was diagnosed as chondromatous hamartoma. Chondromatous hamartoma is a rare subtype of mammary hamartoma, partly composed of chondromatous tissue. It is difficult to differentiate chondoromatous hamartoma from other benign tumors and breast cancer, and a careful comparative diagnosis is required when considering this kind of rare tumor.