Rapidly enlarging tumoral pseudoangiomatous stromal hyperplasia in a 15-year-old patient: distinguishing sonographic and magnetic resonance imaging findings and correlation with histologic findings.

Pseudoangiomatous stromal hyperplasia (PASH) is an uncommon benign lesion of the breast, with a relatively limited number of cases documented in the English literature.(1) Breast tissue affected by PASH is characterized by dense myofibroblastic proliferation of mammary stroma, associated with interanastomosing capillarylike spaces.(2,3) Pseudoangiomatous stromal hyperplasia may present in a wide clinicopathologic spectrum, ranging from focal minor incidental microscopic changes to clinically symptomatic and mammographically evident breast masses.(4,5) Most reported cases of PASH have been small to moderate-sized lesions. There have been few radiologic descriptions of large tumoral PASH.(5-7) We report a case of a 15-year-old patient with bilateral PASH presenting with rapid and massive asymmetric enlargement of the breasts. We describe its sonographic findings with correlative magnetic resonance imaging (MRI) and histopathologic features and highlight an unusual imaging feature not previously described.