Phyllodes tumors (from Greek: "phullon" leaf), also cystosarcoma phyllodes, cystosarcoma phylloides and phylloides tumor, are typically large, fast-growing masses that form from the periductal stromal cells of the breast. They account for less than 1% of all breast neoplasms.
Phyllodes tumors are a fibroepithelial tumor composed of an epithelial and a cellular stromal component. They may be considered benign, borderline, or malignant depending on histologic features including stromal cellularity, infiltration at the tumor's edge, and mitotic activity.
They are classified as a fibroepithelial tumor by ICD-O, but not by MeSH.
Younger women have a higher chance of having a benign phyllodes tumor.
This is predominantly a tumor of adult women, with very few examples reported in adolescents.
Patients typically present with a firm, palpable mass. These tumors are very fast-growing, and can increase in size in just a few weeks. Occurrence is most common between the ages of 40 and 50, prior to menopause. This is about 15 years older than the typical age of patients with fibroadenoma, a condition with which phyllodes tumors may be confused. They have been documented to occur at any age above 12 years.
The common treatment for phyllodes is wide local excision. Other than surgery, there is no cure for phyllodes, as chemotherapy and radiation therapy are not effective. The risk of developing local recurrence or metastases is related to the histologic grade, according to the above-named features. Despite wide excision, a very high percentage of surgeries yielded incomplete excision margins that required revision surgery. Radiation treatment after breast-conserving surgery with negative margins may significantly reduce the
local recurrence rate for borderline and malignant tumors. The authors of a 2012 study have derived a risk calculator for relapse risk of phyllodes tumors after surgery.
Phyllodes tumors are considered to be on a spectrum of disease that consists of fibroadenoma, fibroadenoma variant and benign phyllodes. Some would extend the spectrum to include malignant phyllodes tumors and frank sarcoma.