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Disease Profile

Pseudoangiomatous stromal hyperplasia

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

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Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

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]


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]


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

    Learn more

    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.


        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. https://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..

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