Upon self examination the patient felt a palpable area on her left breast.
A bilateral mammogram was performed on the patient and a large lobulated mass in the inferior left periareolar region was noted, which corresponded with the palpable area.

A targeted bilateral ultrasound was performed on the patient to follow up with the mammographic findings. On ultrasound the palpable area demonstrated a lobulated heterogeneous solid appearing mass in the left breast at 6:00 o'clock which measured 5.3 x 4.6 x 3.4 cm in size. The patient underwent an ultrasound guided needle core biopsy immediatly after the mammogram and ultrasound.
The final pathologic diagnosis states that the specimen demonstrated a biphasic proliferation composed of cleft-like duct structures with "leaf-like" projections and surrounding markedly hypercellular stroma. Cytologic atypia was noted within the stromal component as well as increased mitotic activity. These features suggest the possibility of malignant phyllodes tumor. Complete excision of this tumor is warranted.

Phyllodes tumor is a rare breast tumor that forms from the stroma (connective tissue) of the breast. It is characterized as a rapidly growing mass that is sharply defined with lobulated contours. Its ultrasound appearance is similar to that of a fibroadenoma. On ultrasound the phyllodes tumor appears hypoechoic, with fine or coarse internal echoes, and it has a variable effect on posterior echoes. The phyllodes tumor appears to arise from the connective tissue of the lobule, as does a fibroadenoma. The convoluted hypercellular overgrowth found in this tumor causes elongation and distortion of the ducts that produce slit-like, epithelium lined clefts and cystic spaces. Usually the tumor is more cellular than a fibroadenoma which is evident in the stroma closest to the stretched ducts that are found within the tumor.
Phyllodes tumors may be classified as benign, malignant, or borderline by histologic analysis of mitotic activity, cytologic atypia, and infiltrative versus pushing margins. Increased mitoses characterize the malignant forms. Phyllodes tumors are usually benign but approximately 15% are malignant and are locally invasive, recurrent, or metastatic beyond the breast. Approximately 25% recur locally if not completely removed, and as many as 10% may metastasize (usually to the lung and not to the axillary lymph nodes).
Phyllodes tumors do not respond to hormonal therapy and are less likely to respond to other breast cancer treatments such as chemotherapy or radiation therapy. So the treatment of these tumors is surgical removal. Benign phyllodes tumors are treated by removing the mass and a 2 cm area of normal breast tissue from around the tumor. Malignant phyllodes tumors are removed in the same manner with a wider margin of breast tissue or by total mastectomy if needed.

Kopans, Daniel B. Breast Imaging. 2nd ed. Philadelphia: Lippincott-Raven Publishers, 1998.
American Cancer Society. 2005. 22 April 2005. .

Case Number: 1512497Last Updated: 05-02-2005
Anatomy: Breast   Pathology: Other
Modality: USExam Date: 04-22-2005Access Level: Readable by all users

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