Phyllodes tumors, 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.
Presentation
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.
Diagnosis
Classification
Phyllodes tumors are a fibroepithelial tumorcomposed 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. All forms of phyllodes tumors are regarded as having malignant potential. A large series from the M.D. Anderson Cancer Centre reported the incidence of each as benign, borderline, and malignant. Malignant phyllodes tumours behave like sarcomas and can develop blood-borne metastases. Approximately 10% of patients with phyllodes tumours develop distant metastases and this can go up to 20% in patients with histologically malignant tumours. The commonest sites for distant metastases are the lung, bone, and abdominal viscera. Rare sites of metastasis, such as to the parotid region, have also been described. 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.
Treatment
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.
Spectrum
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.
