What is the pathophysiology of phyllodes tumor (cystosarcoma phyllodes)?

Updated: Jul 23, 2019
  • Author: Donald R Lannin, MD; Chief Editor: John Geibel, MD, DSc, MSc, AGAF  more...
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Answer

Phyllodes tumor is the most commonly occurring nonepithelial neoplasm of the breast, though it represents only about 1% of tumors in the breast. [3]  It has a smooth, sharply demarcated texture and typically is freely movable. It is a relatively large tumor, with an average size of 5 cm (though lesions larger than 30 cm have been reported). The etiology of phyllodes tumors is unknown.

Because of limited data, the relative percentages of benign and malignant phyllodes tumors are not well defined. Reports have suggested, however, that about 85-90% of phyllodes tumors are benign and that approximately 10-15% are malignant. [4]

Although benign phyllodes tumors do not metastasize, they have a tendency to grow aggressively and can recur locally. [3]  Like other sarcomas, malignant phyllodes 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.


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