Pseudoangiomatous stromal hyperplasia (PASH) of the mammary gland: report of a case.

Pseudoangiomatous stromal hyperplasia (PASH) is an uncommon benign breast disease. Pseudoangiomatous stromal hyperplasia is characterized by a collagenous proliferation of mammary stroma, associated with capillary-like spaces. We herein report the case of a 48-year-old woman who presented with a huge mass in her right breast. Physical examination revealed a 20 x 23-cm mass, which was surgically excised. Histopathologically, the tumor was composed of abundant fibrous stroma containing non-vascular slit-like spaces and scattered ducts and lobules. Neither stromal nor epithelial cells showed atypia. We therefore diagnosed the tumor to be PASH.