Pseudoangiomatous stromal hyperplasia (PASH) is an overgrowth of myofibroblastic cells in the breast.

[1] The diagnostic significance is currently uncertain, but it appears to be benign.

There have been cases of PASH diagnosed where the tumors co-exist with breast cancer.

Other cases have made screening for breast cancer difficult and in some cases impossible due to the number and density of the existing PASH tumors.

Excision may be indicated in enlarging masses or lesions with atypical features.