Phyllodes tumors
Phyllodes tumors, also known as cystosarcoma phyllodes, are rare breast tumors that typically originate in the connective tissue of the breast. The term "phyllodes" derives from a Greek word meaning "leaf," reflecting the tumor's leaf-like projections observed under microscopic examination. While the majority of these tumors are benign, about 25 percent can be malignant. They account for a small fraction of breast tumors, comprising approximately 0.3 to 1 percent. Phyllodes tumors can grow slowly over years but may also enlarge rapidly within weeks or months, often discovered during self-examination due to the development of a firm, moveable mass. Diagnosis requires histological analysis, as imaging alone is not sufficient due to the similarities with other breast tumors. Surgical excision is the primary treatment, with the importance of removing a wide margin of surrounding tissue emphasized to reduce recurrence risks. The prognosis for phyllodes tumors is generally favorable, but outcomes can vary significantly, necessitating close monitoring even for benign cases.
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Phyllodes tumors
ALSO KNOWN AS: Phylloides tumors, cystosarcoma phyllodes
RELATED CONDITIONS: Fibroadenomas
DEFINITION: Phyllodes tumors are rare tumors originating in the breast's connective tissue. The term phyllodes comes from a Greek word meaning leaf. The tumor is so named because it has leaf-like projections seen on cross-sections. Most are benign or noncancerous. The malignancy rate is around 25 percent. Phyllodes tumors account for 0.3 to 1 percent of breast tumors.
Risk factors: Women with a history of fibroadenoma, a benign breast tumor, may be at higher risk. Phyllodes tumors are more common in Asian women. Germline mutations of the TP53 gene and the hereditary disorder Li-Fraumeni syndrome are predisposing factors for phyllode tumors.
Etiology and the disease process: The cause of phyllodes tumors is unknown. They develop in the breast's connective, or stromal, tissue and can penetrate ductal tissue or cystic spaces. They usually have a glandular component as well. These tumors may grow slowly for years and then enlarge rapidly over weeks or months. Because of their rapid growth, most phyllodes tumors are discovered on self-examination. If left untreated, they can encompass the entire breast.
Incidence: Phyllodes tumors are rare. The overall risk of malignancy is low, about two per one million women. Phyllodes tumors usually occur in adult women, the average age at diagnosis being forty to fifty years, though they sometimes appear in adolescents or older adults.
Symptoms: The most common symptom of phyllodes tumors is a firm, moveable, rapidly enlarging breast mass. Pressure from the tumor mass can compress the skin of the breast and cause it to appear translucent or bluish with dilated blood vessels. Tumors sometimes break through the skin and cause ulceration. Some tumors are painful. Metastasis, or spread to other parts of the body, from cancerous tumors can cause pain at the site of metastasis. Metastasis is reported in 4 percent of all phyllode tumors and 25 to 31 percent of malignant phyllode tumors.
Screening and diagnosis: Mammograms reveal phyllode tumors as smooth or lobular masses with well-defined borders. Ultrasound examination or other imaging techniques, including computed tomography (CT) and magnetic resonance imaging (MRI), may be used to locate and size phyllode tumors. Still, because of similarities between benign and malignant phyllodes tumors and between phyllodes tumors and fibroadenomas, diagnosis is based on histology, or microscopic examination, of a tumor sample. Fibroadenomas can be diagnosed by needle biopsy and imaging studies, but these methods are not adequate for the diagnosis of phyllode tumors. Excisional or core biopsy is essential to their diagnosis. Histologic factors that help differentiate benign from malignant phyllodes tumors, and both from other tumors, include degree of cellularity, cellular atypia, and growth pattern. Immunostaining of tumor cells helps differentiate phyllode tumors from fibroadenomas because of markedly increased stromal cellularity in phyllode tumors.
Phyllodes tumors are classified as benign, borderline, or malignant. Benign tumors have largely normal cell growth and differentiation. Malignant tumors have many mitotic figures, or rapidly dividing cells (10 or more per 10 high power fields), infiltrating or permeative margins, and marked atypia of cells (2-3+). Borderline tumors have some features of both benign and malignant growths, with 5 to 9 mitotic figures per 10 high power fields, pushing or infiltrating margins, and 2+ cellular atypia. Even within these guidelines, phyllodes tumors are difficult to evaluate, and their growth is unpredictable. For this reason, more than one review of tumor cells is warranted in every case.
Treatment and therapy: The most common treatment for phyllodes tumors is surgical excision, or removal, of the lesion in a lumpectomy procedure. A wide margin of normal cells (one to two centimeters) is removed with the tumor to reduce the chance of recurrence. Mastectomy, or removal of the entire breast, may be the treatment of choice for large tumors or for any tumor that recurs. The treatment is the same for benign and malignant tumors, as chemotherapy, radiation, and hormone therapy have not, in most cases, been effective against cancerous phyllode tumors.
Prognosis, prevention, and outcomes: The prognosis, or most likely outcome, for phyllodes tumors is generally favorable but varies widely because growth and chance of recurrence are unpredictable. The ten-year survival rate for phyllodes tumors is 87 percent, but around 30 percent of individuals with malignant tumors die of the disease. Benign tumors can recur, sometimes with more aggressive or malignant growth. The recurrence rate is 30 percent for phyllode tumors, 23 percent for malignant tumors, and 10 to 17 percent for benign phyllode tumors. The lungs, bones, chest wall, and abdominal organs are the most common sites of metastasis. Metastasis is usually fatal within three years of diagnosis. Because treatment options are limited, close follow-up, even for benign tumors, is essential for the best long-term results.
Bibliography
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