Ductal carcinoma in situ arising within a benign phyllodes tumor: A case report with a review of the literature.

Phyllodes tumor (PT) is a rare type of breast tumor that rarely occurs with breast carcinoma. This study evaluated a 53-year-old female patient with a benign PT with ductal carcinoma in situ (DCIS) within the tumor. A firm, painless, well-demarcated tumor measuring 4-5 cm was noted in the left breast. Over the course of the previous 14 years, the patient underwent excision of a breast tumor four times at the same site in the left breast. The pathological diagnosis of the first tumor was a fibroadenoma (FA), and those of the following three were benign PTs. The tumor was the 5th one noted over the course of the previous 14 years, following the previously recorded surgeries. A firm tumor with a diameter of 3.5 cm was located beneath the scar from the previous surgery, just above the nipple of the left breast. Mammography revealed a high-density irregularly shaped mass with a clear margin. An ultrasound showed low but heterogeneous echogenicity. A computed tomography scan revealed a well-defined enhanced tumor. These image examinations were compatible with recurrent PT. Fine-needle aspiration cytology revealed that the tumor was likely a benign FA. The patient underwent a partial mastectomy with a 1.0 cm margin from the tumor edge, and the firm, attached scar tissue was also resected. Macroscopic examination showed a hard elastic mass, which was encapsulated by thin fibrous tissue and which adhered firmly to the adjacent scar tissue. Microscopic examination showed a 5 mm in diameter DCIS of the cribiform type in a section of the PT epithelial component with an apparently benign stroma. The DCIS cells were strongly positive for estrogen and progesterone receptors, but HER2 expression was negative (score 0). The patient received local irradiation following surgery and no evidence of recurrence or metastasis was detected in the 2 years following surgery. This was a noteworthy case of a DCIS arising in benign PT. To the best of our knowledge, a total of 28 breast carcinomas were previously reported to arise in PT. In this case report, a female patient who presented with a PT was evaluated. A review of the literature is also discussed.