Invasive ductal carcinoma arising in phyllodes tumor with isolated tumor cells in sentinel lymph node

Phyllodes tumor (PT) consists of stroma of variable grading and benign ductal epithelium. Although exceptional, carcinomas that arise from the epithelium in PTs do exist, and seem to behave less aggressively than the usually encountered breast carcinoma. To the best of our knowledge, among the invasive carcinomas that have arisen in PTs, only 1 has been proved to have metastatic carcinoma in the lymph nodes. Here, we describe the youngest woman to have invasive ductal carcinoma that arose in a borderline PT, with isolated carcinoma cells in the sentinel lymph node. Whether such a combined lesion carries a more indolent course is also discussed.