Pseudoangiomatous stromal hyperplasia

Pseudoangiomatous stromal hyperplasia (PASH) is a type of non-cancerous breast lesion. It typically affects women in the reproductive age group. Occasional cases have been described in men, postmenopausal women, adolescents, and children. The size of the lesion varies, but small microscopic PASH is much more common than larger (tumorous) masses. Microscopic PASH is often an incidental finding in breast biopsies done for other non-cancerous or cancerous lesions. Tumorous PASH presents as a firm, painless breast mass or a dense region on a mammogram. The underlying cause of PASH is unclear. There is some evidence in the literature to suggest that hormonal factors may play a role. While PASH itself is benign, it may mimic cancer (specifically angiosarcoma). For this reason, a biopsy may be recommended. Treatment may include observation or surgical excision.