Two Cases of Pseudoangiomatous Stromal Hyperplasia of the Mammary Gland, Including a Case of Rapid Enlargement

Abstract

Pseudoangiomatous stromal hyperplasia (PASH) is a benign tumor composed mainly of stromal proliferation with vascular-like spaces. Herein, we report two cases of PASH, including a case presenting rapid growth.

Case 1 : A 39-year-old woman manifested a left breast mass of 2 cm in diameter. After 2 years, she visited the hospital and found that the mass size increased to 3 cm. It rapidly enlarged to 10.5 cm 1 month later. A needle biopsy showed fibrosis. The patient underwent excision. Pathological examination revealed a vascular-like gap and stromal growth, positive for CD34 and α-smooth muscle actin ; eventually, she was diagnosed with PASH.

Case 2 : A 2.5 cm mass was palpated in the left breast of a 30-year-old woman. Ultrasound revealed a vascular-like gap appearance. Further, a needle biopsy showed stromal growth. We suspected PASH and performed excision.

PASH is a hyperplastic disease with indistinct borders and is difficult to diagnose using biopsy. Although PASH is rare, psuedoangiomatous hyperplasia without mass formation exhibits a high incidence (23%) in some surgical specimens. The concept of this disease should be kept in mind while diagnosing a benign mass.