Smoothelin Is a Specific Marker To Distinguish Muscularis Propria and Muscularis Mucosae in the Gastrointestinal Tract
MA Montani, T Thiesler, G Kristiansen. University Hospital Zurich, Zurich, Switzerland
Background: The unequivocal recognition of anatomical structures relevant for staging is increasingly challenging as tumor specimens and biopsies become ever smaller. So far no marker is available to discriminate reliably between muscularis propria (MP) and muscularis mucosae (MM) of the gastrointestinal tract. Smoothelin has been proposed to differ in MP and MM of the urinary bladder and to aid in diagnostics. We aimed to analyze the expression of smoothelin in MP and MM in order to define a novel diagnostic tool to help identifying MM bundles in the gastrointestinal tract.
Design: Expression of smoothelin and α-smooth muscle actin was analyzed immunohistochemically in gastrointestinal specimens from colon, stomach and esophagus (n=107). For statistics, a two sided Wilcoxon rank test to compare expression levels was used.
Results: In contrast to α-smooth muscle actin which stained MM and MP equally strong, smoothelin expression in MM was either absent or significantly weaker, which was particularly valid in gastric and colon specimens. In samples of the esophagus, however, smoothelin was consistently positive even in the MM, although in direct comparison to MP a slight decrease of intensity was noted (a-c: colon, d-f: stomach, g-i: esophagus; b,e,h: α-smooth muscle actin, c,f,i: smoothelin).
Conclusions: The combination of smoothelin and SMA represents a robust marker combination to discriminate MM from MP in the gastroinstestinal tract, since smoothelin expression in MM is absent or weaker than in MP.
Wednesday, March 24, 2010 9:30 AM
Poster Session V # 53, Wednesday Morning