Extension code 40 Transmural, NOS invasion through muscularis into (sub)serosal tissue/fat
Invasion through the wall to the subserosal tissues or fat is assigned code 40. “Through the wall” means invasion of the intestinal wall into subserosal tissue and is coded to 40. Invasion of subserosal tissue is not beyond the organ of origin. These are AJCC T3 lesions, but the summary stage is local.