Author: Nat Pernick, M.D. (see Authors page)

Revised: 28 April 2017, last major update November 2011

Copyright: (c) 2002-2017,, Inc.

Cite this page: Smoothelin. website. Accessed July 21st, 2018.
Definition / general
  • Distinction of cytoplasmic from nuclear staining may be important
Uses by pathologists
Microscopic (histologic) images

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Lamina propria: Muscularis mucosae (arrowhead); Detrusor muscle (arrow)

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Various images

Positive staining - normal
  • Differentiated smooth muscle cells
Positive staining - disease
  • Cytoplasmic staining: benign smooth muscle tumors, GI leiomyosarcomas (24%, Am J Surg Pathol 2009;33:1795
  • Nuclear staining: GI leiomyosarcomas (41%), GIST (22%)
Negative staining
  • Striated muscle, myofibroblasts, myoepithelial cells, pericytes
  • Negative cytoplasmic staining in dedifferentiated liposarcoma, desmoid tumor, GIST, inflammatory myofibroblastic tumor, MPNST, schwannoma