Pseudoangiomatous stromal hyperplasia of the breast in pediatric patients: an underrecognized entity.

Pseudoangiomatous stromal hyperplasia (PASH) is a benign lesion consisting of mammary stromal proliferation with anastomosing slits mimicking vascular spaces. Grossly, it most often resembles fibroadenoma, but may commonly be confused with angiosarcoma and other types of benign vascular proliferations. While PASH has been described in female and male adults since the mid-1980s, there have been only a few accounts in the pediatric population. We present a series of 12 pediatric patients with PASH, including a 3-year-old male, who we believe to be the youngest patient to present with this entity. In our study, PASH was found in 12% of tumors diagnosed preoperatively as fibroadenomas and in 12% of cases diagnosed preoperatively as gynecomastia. Our series documents that PASH is not uncommon in pediatric breast pathology and delineates important differences between adult and pediatric presentations of this entity.