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Smooth Muscle Actin (SMA)

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  • Actin expression in pericytes surrounding a small blood vessel. Note the endothelial cells are negative.
  • "Tram track" pattern of actin expression in myofibroblasts.
  • "Tram track" pattern of actin expression in myofibroblasts.
  • "Tram track" pattern of actin expression in myofibroblasts.
  • Actin expression in PEComa.
  • Actin expression in a rare example of angiomyolipoma with epithelial cyst. Most of the ovarian-like stroma cells (adjacent to cyst epithelium) are negative for actin.
  • Actin expression in normal glomerulus and adjacent blood vessel.
  • Smooth muscle actin expression in glomangioma/glomus tumor.
  • Smooth muscle actin expression in pilar leiomyoma.



Technical InfoEdit

Staining PatternEdit

Expression in Normal TissuesEdit

Expression in Neoplastic EntitiesEdit

Intermediate/Uncertain Malignant PotentialEdit
  • Glomus tumor[1]


Expression in Non-Neoplastic EntitiesEdit

Pertinent NegativesEdit

This antigen is typically NOT expressed by the following entities:

Practical Uses / PanelsEdit

Common PitfallsEdit

Related Links/Other ResourcesEdit


  1. Folpe AL, Fanburg-Smith JC, Miettinen M, Weiss SW. Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors. Am J Surg Pathol. 2001;25(1):1-12

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