Pseudoangiomatous Stromal Hyperplasia of the Breast: Clinical, Radiologic and Histopathologic Spectrum in a Retrospective Single‐Centre Series

PURPOSE: Pseudoangiomatous stromal hyperplasia (PASH) is a benign mesenchymal breast lesion with a broad spectrum of clinical and radiologic presentations. We aimed to evaluate the demographic, radiologic and histopathologic features of PASH-containing breast lesions. METHODS: This retrospective single-centre study included patients with histopathologically confirmed PASH identified between January 2019 and January 2026. Clinical records, mammography, ultrasonography, MRI findings and pathology reports were reviewed. Imaging findings were analysed descriptively together with demographic and histopathologic characteristics. RESULTS: Thirty-one female patients with a mean age of 34.1 ± 11.7 years (range, 11-51 years) were included. Most patients were premenopausal (29/31, 94%). PASH was most commonly identified as an incidental or associated stromal finding, particularly in fibroadenoma-spectrum lesions (18/31, 58%). On ultrasonography, the predominant appearance was an oval, parallel-oriented, hypoechoic lesion with circumscribed margins, although suspicious findings such as indistinct margins and non-parallel orientation were also observed. Mammographic findings ranged from negative examinations to mass-like densities and calcifications. MRI appearances were heterogeneous and included both mass and non-mass enhancement patterns. Two young patients demonstrated rapidly enlarging dominant diffuse/nodular PASH lesions with diffusion restriction on MRI, raising preoperative suspicion for angiosarcoma and ultimately requiring surgical management. CONCLUSION: Breast PASH demonstrates substantial biologic and radiologic heterogeneity, ranging from incidental stromal findings within benign proliferative lesions to rapidly enlarging diffuse/nodular masses with aggressive imaging features mimicking angiosarcoma. Because imaging findings may reflect both the PASH component and associated breast pathology, radiologic-pathologic correlation is essential for accurate diagnosis and appropriate management.