Pseudoangiomatous stromal hyperplasia (PASH) is a relatively uncommon histologic finding in breast specimens. The clinicopathologic spectrum of this disease entity can range from a focal nonsignificant microscopic finding to a dominant palpable breast mass. To confirm the diagnosis, a biopsy is required primarily to distinguish PASH from a low-grade angiosarcoma. The mammographic description of PASH is a round or ovoid, circumscribed or partially circumscribed mass. The sonographic feature is a hypoechoic mass. PASH is similar to a fibroadenoma in clinical and imaging features. Progressive breast enlargement associated with engorgement, cyclical breast pain, and burning sensation is of significant concern for some women. The management of the palpable mass and associated symptoms has included excisional biopsy, often leading to recurrent excisions and even mastectomy. This report documents an impressive response to tamoxifen in a patient with PASH presenting with breast enlargement, pain, and breast masses. To our knowledge, there are no reports on the use of tamoxifen or other selective estrogen receptor modulators in the management of this benign breast condition.