h-Caldesmon as a specific marker of smooth muscle cell differentiation in some soft tissue tumors of the skin.
BACKGROUND
An existing problem in contemporary pathology is the classification and distinction of spindle cell soft tissue tumors of the skin. Markers such as alpha-smooth muscle actin (alpha-SMA) and desmin, considered specific for smooth muscle cell (SMC), have been shown to be expressed in a variety of fibroblastic and myofibroblastic processes. High-molecular-weight caldesmon (h-caldesmon), one of two isoforms, is reported to be expressed exclusively by SMC and has recently been shown to be a specific marker of SMC tumors.


METHODS
Tumors were obtained from 11 patients taken from the surgical pathology archives of the University of South Florida and cases were coded as smooth muscle hamartoma, myofibroma, and dermatomyofibroma.


RESULTS
The case of smooth muscle hamartoma had greater than 90% of tumor cells labeling with anti-h-caldesmon antibodies. Three of three cases of myofibroma had focal areas of positivity representing less than 10% of total tumor cells. Seven of seven dermatomyofibromas showed no apparent labeling with anti-h-caldesmon antibody. Dense reactivity was noted in vascular wall smooth muscle, indicating internal controls.


CONCLUSIONS
We can conclude that h-caldesmon is a specific marker of fully differentiated smooth muscle and that it can serve to differentiate spindled SMC soft tissue tumors of the skin from tumors of myofibroblastic and/or fibroblastic origin.
D'Addario
Stephen F
SF
Department of Pathology, University of Arkansas for Medical Sciences, 4301 W. Markham, Little Rock, AR 72205, USA.
Morgan
Michael
M
Talley
Lori
L
Smoller
Bruce R
BR
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D005260:Female; D005350:Fibroma / Q000378:metabolism / Q000473:pathology; D006222:Hamartoma / Q000378:metabolism / Q000473:pathology; D018219:Histiocytoma, Benign Fibrous / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019042:Muscle Neoplasms / Q000378:metabolism / Q000473:pathology*; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology*; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*
D014408:Biomarkers, Tumor; D002148:Calmodulin-Binding Proteins