Abstract
Pseudoangiomatous stromal hyperplasia (PASH) in male patients is a rare condition that represents a hormonally-induced proliferation of mesenchymal tissue of the breast. This benign pathology is often undiagnosed due to many reasons. When PASH presents as a breast mass, it appears innocent, developing as a smooth and well-circumscribed tumor. Furthermore, it does not elicit suspicious findings on imaging. These points often halt further investigation of many breast abnormalities. Breast masses are statistically most likely to be gynecomastia when they arise in men. However, they are important to investigate because, although rare, breast cancer can occur in men. Furthermore, the benign conditions of the breast that commonly affect women can also impact male patients. It is oftentimes overlooked that men too can experience hormonal stimulation of the breast tissue. The following case describes this rare but important instance of a male patient diagnosed with PASH following a previous diagnosis of infiltrative ductal carcinoma in situ of the contralateral breast.