Cystosarcoma phyllodes is a rare, predominantly benign tumor of the breast. Its name is derived from the Greek words sarcoma (“fleshy tumor”), and phyllon (“leaf”). Grossly, the tumor displays characteristics of a large, malignant sarcoma, takes on a leaflike appearance when sectioned, and displays epithelial, cystlike spaces when viewed histologically. Because most tumors are benign, the name may be misleading. Thus, the favored terminology is now phyllodes tumor.
Pathophysiology and etiology
Phyllodes tumor is the most commonly occurring nonepithelial neoplasm of the breast. It has a smooth, sharply demarcated texture and typically is freely movable. It is a relatively large tumor, with an average size of 5cm. The etiology of phyllodes tumors is unknown.
While most phyllodes tumors are benign, the possibility exists for underestimating their potential for malignancy. Moreover, some juvenile fibroadenomas in teenagers can look histologically like phyllodes tumors; however, they behave in a benign fashion similar to that of other fibroadenomas.
Because of limited data, the percentage of benign versus malignant phyllodes tumors is not well defined. Reports suggest, however, that about 85-90% of phyllodes tumors are benign and that approximately 10-15% are malignant.
Although the benign tumors do not metastasize, they have a tendency to grow aggressively and can recur locally. Like other sarcomas, the malignant tumors metastasize hematogenously. Unfortunately, the pathologic appearance of a phyllodes tumor does not always predict the neoplasm’s clinical behavior; in some cases, therefore, there is a degree of uncertainty about the lesion’s classification.
The characteristics of a malignant phyllodes tumor include the following:
Recurrent malignant tumors seem to be more aggressive than the original tumor
The lungs are the most common metastatic site, followed by the skeleton, heart, and liver
Symptoms of metastatic involvement can arise from as early as a few months to as late as 12 years after the initial therapy
No cures for systemic metastases exist
History & Physical Examination
Phyllodes tumors generally manifest as larger masses and display rapid growth. A small mass may rapidly increase in size in the few weeks before the patient seeks medical attention. Tumors rarely involve the nipple-areola complex or ulcerate to the skin. Patients with metastases may present with such symptoms as dyspnea, fatigue, and bone pain.
A firm, mobile, well-circumscribed, nontender breast mass is appreciated. Overlying skin may display a shiny appearance and be translucent enough to reveal underlying breast veins. A very large phyllodes tumor may erode through overlying skin and present as an external fungating breast mass.
Image: Benign phyllodes on mammogram
Open excisional breast biopsy for smaller lesions and incisional biopsy for large lesions are the definitive methods for diagnosing phyllodes tumors.
Fine-needle aspiration for cytologic examination usually is inadequate for the diagnosis of phyllodes tumors. Core biopsy is more reliable, but sampling errors may still occur, and it may still be difficult to distinguish the lesion from a fibroadenoma.
Complete excision, with accurate histologic examination and continued follow-up care, is the best way to treat phyllodes tumors. In most cases of cystosarcoma phyllodes, wide local excision is indicated, with a rim of normal tissue included.
The lesion should not be “shelled out,” as might be done with a fibroadenoma, or the recurrence rate will be unacceptably high.
If the tumor-to-breast ratio is sufficiently high to preclude a satisfactory cosmetic result with segmental excision, simple mastectomy with or without reconstruction, is an alternative. Axillary lymph nodes are involved in less than 10% cases with malignant phyllodes and axillary lymph node dissection is usually not required during surgery.
In patients with recurrent phyllodes tumors, re-excision should be performed. Adjuvant radiotherapy can be used to reduce recurrence rates.