Pseudoangiomatous stromal hyperplasia

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Pseudoangiomatous stromal hyperplasia
Diagnosis in short

Pseudoangiomatous stromal hyperplasia. H&E stain.

LM abundant breast stroma, small complex inter-anastomosing (blood vessel/capillary-like) channels
LM DDx fibroadenoma, low-grade angiosarcoma
Stains Bcl-2 +ve, vimentin +ve, CD34 +ve, SMMHC +ve, CD31 -ve, factor VIII -ve
Site breast

Signs +/-breast mass
Prevalence uncommon
Prognosis benign
Clin. DDx fibroadenoma
Treatment followup or excision

Pseudoangiomatous stromal hyperplasia, abbreviated PASH, is benign lesion is breast pathology.

It is also known as nodular myofibroblastic stromal hyperplasia of the mammary gland.[1]


  • Benign lesion.
  • Thought to arise due to myofibroblast abnormality - though not well understood.[2]
  • An incidental finding or occasionally a mass.[3]
  • May be suspicious on imaging (BI-RADS 4 or 5).[4]
  • May be followed (expectant management) or (surgically) excised.[5]



  • May form mass.
    • Grey-white & firm.
    • Well-circumscribed borders.



  • Abundant breast stromal.
  • Small, complex, inter-anastomosing (blood vessel/capillary-like) channels - key feature.
    • Pseudoangiomatous = blood vessel-like.


  • May mimic angiosarcoma at low power; PASH may have the same architecture but lack nuclear atypia.
  • Occasionally has mitotic activity - proliferative PASH.






  • CD34 +ve.
  • Vimentin +ve.
  • Bcl-2 +ve.[8][9]
  • Factor VIII -ve.
  • CD31 -ve.[8]

See also


  1. Leon, ME.; Leon, MA.; Ahuja, J.; Garcia, FU.. "Nodular myofibroblastic stromal hyperplasia of the mammary gland as an accurate name for pseudoangiomatous stromal hyperplasia of the mammary gland.". Breast J 8 (5): 290-3. PMID 12199757.
  2. 2.0 2.1 2.2 Powell CM, Cranor ML, Rosen PP (March 1995). "Pseudoangiomatous stromal hyperplasia (PASH). A mammary stromal tumor with myofibroblastic differentiation". Am. J. Surg. Pathol. 19 (3): 270–7. PMID 7872425.
  3. Drinka, EK.; Bargaje, A.; Erşahin, ÇH.; Patel, P.; Salhadar, A.; Sinacore, J.; Rajan, P. (Feb 2012). "Pseudoangiomatous stromal hyperplasia (PASH) of the breast: a clinicopathological study of 79 cases.". Int J Surg Pathol 20 (1): 54-8. doi:10.1177/1066896911418643. PMID 21862488.
  4. Wieman, SM.; Landercasper, J.; Johnson, JM.; Ellis, RL.; Wester, SM.; Lambert, PJ.; Ross, LA. (Dec 2008). "Tumoral pseudoangiomatous stromal hyperplasia of the breast.". Am Surg 74 (12): 1211-4. PMID 19097540.
  5. Jaunoo, SS.; Thrush, S.; Dunn, P. (2011). "Pseudoangiomatous stromal hyperplasia (PASH): a brief review.". Int J Surg 9 (1): 20-2. doi:10.1016/j.ijsu.2010.09.005. PMID 20887819.
  6. Vuitch MF, Rosen PP, Erlandson RA (February 1986). "Pseudoangiomatous hyperplasia of mammary stroma". Hum. Pathol. 17 (2): 185–91. PMID 3949338.
  7. 7.0 7.1 Ferreira, M.; Albarracin, CT.; Resetkova, E. (Feb 2008). "Pseudoangiomatous stromal hyperplasia tumor: a clinical, radiologic and pathologic study of 26 cases.". Mod Pathol 21 (2): 201-7. doi:10.1038/modpathol.3801003. PMID 18084246.
  8. 8.0 8.1 Baker, M.; Chen, H.; Latchaw, L.; Memoli, V.; Ornvold, K. (Aug 2011). "Pseudoangiomatous stromal hyperplasia of the breast in a 10-year-old girl.". J Pediatr Surg 46 (8): e27-31. doi:10.1016/j.jpedsurg.2011.04.063. PMID 21843705.
  9. URL: Accessed on: 28 April 2012.