Invasive mucinous carcinoma arising within breast fibroadenoma

Malignant neoplasms arising in the epithelial component of breast fibroadenomas are rare. The most frequent types are lobular and ductal intra-epithelial carcinomas, with a minority of infiltrating carcinoma. We report a case of 36-year-old patient with invasive mucinous carcinoma (30 x 30 mm) arising in a complex breast fibroadenoma (130 x 60 x 30 mm). The patient underwent mastectomy with dissection of the axillary lymph nodes, which were free of tumour. The patient is alive without disease five years later. To the best of our knowledge, this is the first report of an invasive mucinous carcinoma arising within breast fibroadenoma. Our case provides information about the clinicopathologic characteristic of this unusual tumour.