Pseudoangiomatous stromal hyperplasia: overview and clinical management

Abstract

: Pseudoangiomatous stromal hyperplasia (PASH) is a benign mesenchymal lesion of the breast characterized by dense collagenous stroma forming “pseudoangiomatous” capillary-like spaces lined by slender spindle cells. A rare condition overall, PASH is most common in premenopausal women, though cases have been described at ages ranging from 14 to 86, and in men, usually associated with gynecomastia. While the exact etiology is unknown, PASH is considered hormonally responsive, with myofibroblastic proliferation leading to stromal hyperplasia. It may present as a palpable mass or an incidental imaging finding. The usual appearance on mammography and ultrasound is that of a well-circumscribed mass which must be differentiated from other benign and malignant lesions such as fibroadenoma, phyllodes tumor, and myofibroblastoma; histologically it must be distinguished from angiosarcoma. Core needle biopsy is indicated for diagnosis and must be concordant with imaging and clinical findings. PASH lesions should be surgically excised if enlarging, associated with symptoms, suspicious imaging findings are present, or other lesions are synchronously diagnosed that warrant removal; otherwise, observation with clinical and imaging follow-up can be considered. Progression and recurrence, each reported at rates of approximately 15–20%, indicate change in management and/or additional surgical intervention. PASH is not associated with an increased risk of breast cancer and prognosis is generally favorable.