label: Pseudoangiomatous Stromal Hyperplasia
label_lc: pseudoangiomatous stromal hyperplasia
description: A benign proliferation of the stromal cells in the breast.  It is classified as simple, when associated with the presence of slit-like spaces without erythrocytes and as fascicular/proliferative, when spindle cell proliferation without atypia is present.  It is often seen in breast tissue specimens as small foci associated with benign epithelial lesions.  Pseudoangiomatous stromal hyperplasia presenting as a well-circumscribed palpable mass is rare.