Pseudoangiomatous stromal hyperplasia (PASH) is a benign disease of the breast characterized by a complex network of slitlike spaces lined by slender spindle cells within a background of stromal hyperplasia [1] (Figs. 1C and 1D). The etiologic factors of PASH are unknown, but most investigators think that it represents a proliferative response of myofibroblasts, probably to hormonal stimuli [1–3]. The purpose of the present study was to describe the imaging appearance of PASH with pathologic and clinical correlation.
We performed a retrospective review of our institution's surgical pathology database for the histologic diagnosis of PASH from January 1998 through December 2006. Cases without available imaging results or in which PASH was an incidental finding were excluded. We identified 57 cases, all in female subjects (mean age, 48 years; range, 9–76 years), for which PASH was the sole or dominant pathologic finding and for which imaging results were available. Diagnosis was obtained for 48 patients from percutaneous biopsies: two en bloc 12-mm radiofrequency biopsies, 12 biopsies with vacuum-assisted devices (9- and 11-gauge), and 34 core needle biopsies (14-gauge needle, 29 biopsies; 16-gauge needle, three biopsies; and 18-gauge needle, two biopsies). Nine cases were identified from excisional biopsies.