Mesenchymal tumors of muscularis mucosae of colon and rectum are benign leiomyomas that should be separated from gastrointestinal stromal tumors—a clinicopathologic and immunohistochemical study of eighty-eight cases - Miettinen,M.; Sarlomo-Rikala,M.; Sobin,L.H. (Mod Pathol, 2001)