Pseudoangiomatous stromal hyperplasia (PASH) is a rare, benign (noncancerous) breast lesion. It can present as a dense mass that can only sometimes be felt when palpating the breast.
That mass is caused by an overgrowth of myofibroblastic cells. These are a cross between cells found in connective tissues and cells found in smooth muscles. While infrequent, PASH can also manifest itself with severe breast enlargement.
Even when PASH does produce a palpable mass, it’s often painless. That’s why the condition is usually found incidentally, such as during a routine mammogram.
PASH affects mostly women and can occur at any age, but it’s generally found in women during their premenopausal or perimenopausal years.
In some cases, a PASH mass is microscopic and produces no symptoms. However, PASH can also present as a larger mass. When the mass can be felt, it’s usually firm and moveable.
What causes PASH is unknown, but experts suspect there may be a hormonal link.
Research published in the journal
According to a 2010 study, the answer is no. In fact, the study found that women with PASH had a lower risk of breast cancer, though they cannot explain why.
The study looked at over 9,000 biopsies performed in women with benign breast disease. While women with PASH tended to be younger than the other study participants, the two groups had similar family medical histories when it came to breast cancer.
In many cases, PASH is an incidental diagnosis. It often occurs when a woman is having a routine mammogram or undergoing a breast biopsy for another breast condition like fibroadenoma. (Fibroadenoma is another type of painless breast lump that can be confused with PASH.)
Whenever a breast lump is discovered, it’s best to check in with a doctor. They may order additional imaging tests, like an ultrasound or MRI. They may also suggest you undergo a core needle biopsy.
This is a procedure that’s usually done using a local anesthetic to numb the area. During the procedure, a hollow needle is inserted into the breast to remove tissue for sampling. The sample is then sent to a lab for evaluation and a definitive diagnosis.
For PASH masses that are not producing symptoms, your doctor may recommend a wait-and-watch approach. The masses do tend to grow over time, and regular follow-up (often with mammography) is advised.
Some women may prefer having the mass removed. This may be a good option if you have a family history of breast cancer, if the mass is large and causing symptoms, or if it’s just generally making you uneasy.
This is typically done via a lumpectomy. A lumpectomy is a surgical removal of the mass and some surrounding tissue. The procedure is performed under general anesthesia, usually in an outpatient center.
Even with removal, PASH can return. Roughly, 7-26% of people will have a recurrence of PASH. Surgeons often cut out a wide margin of healthy tissue around the mass to help prevent a regrowth.
PASH is a rare condition. Research from the journal
Because the condition can mimic breast cancer as well as noncancerous breast lumps like fibroadenomas, it needs investigation, evaluation, and follow-up. Make an appointment with your doctor at the first notice of a breast lump and follow recommended guidelines for mammograms.