Intracystic Papillary Carcinoma, with Focal Invasion

The patient is a 77 year old woman who underwent excision of a 2.0 cm, palpable mass in the right breast. The upper left photo is a low power view of the tumor surrounded by a relatively thick fibrous capsule.  The tumor consists of numerous papillae. At higher magnification (upper right), the papillae show fibrovascular cores lined by a layer of uniformly atypical epithelial cells.  No myoepithelial cells are seen beneath the epithelial layer, a feature distinguishing intracystic papillary carcinoma from intracystic papilloma. Immunohistochemistry  for smooth muscle heavy-chain myosin, a myoepithelial marker, confirms the absence of myoepithelial cells (lower left). Focally, in the lower right photo, there is stromal invasion manifested by the presence of irregular clusters of tumor cells in the adjacent stroma.

Papillary carcinoma constitutes 1-2% of breast carcinomas. It carries a similar prognosis to other intraductal carcinomas when it is non-invasive and a significantly better prognosis than usual ductal carcinoma when invasive. The lesions are usually well-circumscribed and about one-half are located near the nipple and associated with a bloody discharge.

Contributed by Dr. Cunxian Zhang