Stains & CD markers
Actin - muscle specific
Copyright: 2003-2023, PathologyOutlines.com, Inc.
PubMed Search: Muscle specific actin[title]
Actin - muscle specific
Author: Nat Pernick, M.D.
Last author update: 1 September 2013
Last staff update: 23 June 2021
Copyright: 2003-2023, PathologyOutlines.com, Inc.
PubMed Search: Muscle specific actin[title]
Table of Contents
Definition / general | Uses by pathologists | Microscopic (histologic) images | Positive staining - normal | Positive staining - disease | Negative stainingCite this page: Pernick N. Actin - muscle specific. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsactinmusclespecific.html. Accessed June 9th, 2023.
Definition / general
- Discovered in 1987 (Am J Pathol 1987;126:51); also called HHF35, MSA
- Recognizes all alpha actins (skeletal, smooth, cardiac) and gamma smooth muscle actin; but not beta cytoplasmic or gamma cytoplasmic actin (the latter is also called non-muscle actin)
- Recognizes actin expressed in all cells with muscle differentiation (cardiac, smooth and skeletal muscle), myoepithelial cells, myofibroblasts, pericytes and myogenic tumors (Am J Clin Pathol 1991;96:32)
Uses by pathologists
- Identify skeletal muscle (Tumori 2007;93:198, J Cutan Pathol 2007;34:352) and smooth muscle cells (Eur Respir J 2001;17:316) in normal tissue or various disease entities
- Classify tumors with smooth or skeletal muscle, pericytes, myofibroblasts (Cardiovasc Pathol 2006;15:91) or myoepithelial cells
- Differentiate leiomyosarcoma (MSA+, keratin-) from spindle cell carcinoma (MSA-, keratin+, Am J Otolaryngol 2005;26:201)
Microscopic (histologic) images
Images hosted on other servers:
Endometriosis
Myofibroblastoma: breast (fig d)
Myofibroblastoma: lymph node
Rhabdomyo-sarcoma: CNS, embryonal (fig 4)
Rhabdomyo-sarcoma: oral cavity
Glomus tumor
Positive staining - normal
- Cardiac muscle, decidua, myoepithelial cells (although calponin and vimentin may be better, Braz Dent J 2007;18:192), myofibroblasts, pericytes, skeletal muscle, smooth muscle and vascular smooth muscle
Positive staining - disease
- Adenoid cystic carcinoma-myoepithelial component (J Oral Maxillofac Surg 2006;64:415)
- Angiomyolipoma
- Cardiac rhabdomyoma
- Chondroblastoma (35%, Hum Pathol 1997;28:316)
- Endometriosis-smooth muscle (Hum Reprod 2000;15:767)
- Fibromatosis (Acta Cytol 1991;35:403)
- Giant cell tumor of bone (Ultrastruct Pathol 2013;37:183)
- Glioblastoma multiforme (occasional)
- Glomus tumor (Hum Pathol 1999;30:1259)
- Inflammatory myofibroblastic tumor (Mod Pathol 2001;14:784)
- Leiomyoma (Int J Gynecol Pathol 1995;14:134)
- Leiomyosarcoma (80-100%, J Pak Med Assoc 2005;55:138, APMIS 1997;105:793, Histopathology 2013;63:194)
- Malignant fibrous histiocytoma (30%, J Clin Pathol 2003;56:666)
- Mucinous cystic neoplasm (ovarian type stroma, Saudi Med J 2013;34:80), although most studies report smooth muscle actin (Am J Surg Pathol 1999;23:1)
- Myoepithelioma (Zhonghua Bing Li Xue Za Zhi 2005;34:211)
- Myofibroblastic sarcoma (Chin Med J (Engl) 2007;120:363, Hum Pathol 2008;39:846)
- Myofibroblastoma (variable)
- Myofibroma (Histopathology 2012;60:E1)
- Myopericytoma (Hum Pathol 2010;41:1500)
- Osteosarcoma (Am J Clin Pathol 2000;113:663)
- Perivascular epithelioid cell tumors (Diagn Pathol 2012;7:183), although most studies report smooth muscle actin
- Pleomorphic adenoma (Hum Pathol 1991;22:1206)
- Rhabdomyosarcoma (but MyoD1 and myogenin are more specific / sensitive, Am J Surg Pathol 2006;30:962)
- Sinonasal-type hemangiopericytoma (Head Neck 2005;27:124, Am J Surg Pathol 2003;27:737)
- Solitary fibrous tumor (variable staining, Mod Pathol 1997;10:443)
Negative staining
- Angiomyofibroblastoma (Pathol Int 1995;45:487), mesothelioma-epithelioid (Am J Surg Pathol 2006;30:463)
