National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Pseudoangiomatous stromal hyperplasia

Not a rare disease Not a rare disease
Other Names:
PASH; Mammary pseudoangiomatous stromal hyperplasia; Pseudoangiomatous stromal hyperplasia of the breast
Pseudoangiomatous stromal hyperplasia (PASH) is a type of non-cancerous breast lesion. It typically affects women in the reproductive age group.[1][2] Occasional cases have been described in men, postmenopausal women, adolescents, and children.[2] 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.[1][2][3] 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.[2]  
Last updated: 7/14/2016
Surgical removal of the PASH lesions has been performed in some individuals. A wide margin around the mass may be removed to prevent recurrence. Although PASH lesions often grow over time and may recur, they are neither associated with malignancy (cancer) nor considered to be premalignant (pre-cancerous).[3] According to the medical text, CONN's Current Therapy 2007, approximately 7 percent of people experience a recurrence of PASH.[4]
Last updated: 7/19/2013

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Providing General Support

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • The American Cancer Society provides information on benign (non-cancerous) breast conditions.  Click on the American Cancer Society link to view this information.

In-Depth Information

  • PubMed is a searchable database of medical literature and lists journal articles that discuss Pseudoangiomatous stromal hyperplasia. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Virk RK, Khan A. Pseudoangiomatous stromal hyperplasia: an overview. Arch Pathol Lab Med. 2010 Jul; 134(7):1070-4. https://www.ncbi.nlm.nih.gov/pubmed/20586640.
  2. Bowman E, Oprea G, Okoli J, Gundry K, Rizzo M, Gabram-Mendola S, Manne U, Smith G, Pambuccian S, and Bumpers HL. Pseudoangiomatous Stromal Hyperplasia (PASH) of the Breast: A Series of 24 Patients.. Breast J. 2012 May-Jun; 18(3):242-247. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3658111/.
  3. Cyrlak D, Carpenter PM. Breast imaging case of the day: Pseudoangiomatous stromal hyperplasia. Radiographics. 1999; 19:1086-1088. http://pubs.rsna.org/doi/full/10.1148/radiographics.19.4.g99jl201086.
  4. Sukumvanich P, Borgen P. Diseases of the Breast. In: Rakel RE, Bope ET. CONN'S Current Therapy 2007, 59th ed. Philadelphia, PA: Saunders Elsevier; 2007..