Pseudoangiomatous Stromal Hyperplasia
Definition
- Microscopic or clinically apparent breast lesion of variable cellularity featuring dense collegenous stroma punctuated by slit like spaces
Alternate/Historical Names
- Nodular myofibroblastic stromal hyperplasia of the mammary gland
- PASH
- Pseudoangiomatous hyperplasia of mammary stroma
Diagnostic Criteria
- May be a circumscribed mass or microscopic incidental finding
- Masses reported ranging from 0.8 - 11 cm
- Dense hyalinized collagen bundles
- May expand intralobular stroma
- Surrounds ducts and lobules
- Usually circumscribed but merges with surrounding stroma
- Anastomosing pseudovascular slit like spaces punctuate collagen bundles
- No true vascular lining or structure
- No erythrocytes in spaces
- Spaces often lined by spindle cells with range of cellularity
- Classically almost inconspicuous, discontinuous flat bland cells
- One male case described with multinucleated cells
- Classical areas also present in all cellular cases described
- Spectrum of increased cellularity
- Cells associated with spaces more numerous and larger
- Nuclei may be larger and vesicular
- Increased cellularity may obscure or obliterate pseuovascular spaces
- May show marked cellularity with bundles and fascicles of cells
- May predominate over collagenous stroma
- CD34 positive but CD31 and Factor VIII negative
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting: May 1, 2006
Last Update: March 16, 2008
- Masses reported ranging from 0.8 - 11 cm
- May expand intralobular stroma
- Surrounds ducts and lobules
- Usually circumscribed but merges with surrounding stroma
- No true vascular lining or structure
- No erythrocytes in spaces
- Classically almost inconspicuous, discontinuous flat bland cells
- One male case described with multinucleated cells
- Classical areas also present in all cellular cases described
- Spectrum of increased cellularity
- Cells associated with spaces more numerous and larger
- Nuclei may be larger and vesicular
- Increased cellularity may obscure or obliterate pseuovascular spaces
- May show marked cellularity with bundles and fascicles of cells
- May predominate over collagenous stroma
- Cells associated with spaces more numerous and larger
- CD34 positive but CD31 and Factor VIII negative
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting: May 1, 2006
Last Update: March 16, 2008
