Malignant cystosarcoma phyllodes a case report with cytologic presentation.

The cytologic findings in a fine-needle aspirate of a malignant cystosarcoma phyllodes of the breast are presented. They are characterized by the presence of mononucleated and multinucleated sarcoma cells and clusters of normal or hyperplastic duct epithelial cells. The histogenesis and subclassification of the stromal portion of this rare neoplasm are discussed.