Originally described by Johannes Muller in 1838, phyllodes tumors comprise less than 1% of all breast tumors.1Although they closely resemble fibroadenomas,
they are distinguished by larger size, rapid growth, and late occurrence.
The overlying skin may show dilated veins, bluish discoloration, and,
rarely, pressure necrosis, although frank ulceration is uncommon.2Rarely, pressure necrosis of the overlying skin can occur with a huge benign phyllodes tumor,3more so in a small breast. This, coupled with the growth stimulus of pregnancy, can cause extrusion of the tumor through the skin, as was seen in the present case. When it extrudes out of the skin, the exophytic lump can be mistaken for an aggressive malignant tumor. About 40% manifest estrogen receptors, and almost 100% are progesterone receptor positive,4which explains their rapid growth during pregnancy. Mammographic features resemble those of a fibroadenoma. On fine-needle aspiration cytological examination, cohesive stromal cells, mesenchymal cells,
clusters of hyperplastic ductal cells, foreign body giant cells, bipolar naked nuclei, and absence of apocrine metaplasia are highly suggestive of phyllodes tumor.5On histological examination, hypercellular stroma is seen to project into epithelial-lined cystic spaces. The stroma is the neoplastic component and determines the behavior of the tumor. Based on the margin, infiltration, tumor necrosis, stromal cellularity, atypia, and number of mitoses per high-power field, these can be classified as benign, borderline, or malignant.6