Bilateral pseudoangiomatous stromal hyperplasia tumors in axillary male gynecomastia: report of a case.

Pseudoangiomatous stromal hyperplasia (PASH) is a rare benign proliferation of breast stromal cells with a complex pattern of interanastomosing spaces lined by myofibroblasts. The exact etiology is still unknown, but a proliferative response of myofibroblasts to hormonal stimuli has been postulated. PASH is a relatively common incidental finding in breast tissue removed for other reasons and rarely manifests as a localized mass. Fewer than 150 cases of tumoral PASH have been reported since it was first described in 1986. Although PASH tends to grow over time, most lesions are cured by surgical excision and the prognosis is excellent. We report an unusual case of bilateral axillary tumoral PASH in a 44-year-old man. Awareness of this disease is important when considering the differential diagnosis of axillary masses. To our knowledge, only one other case of unilateral axillary tumoral PASH in a male patient has been described in English and this is the first case of PASH occurring in male bilateral axillary gynecomastia.