NCIt synonyms : PASH; Breast Pseudoangiomatous Stromal Hyperplasia;
NCIt definition : 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.;