Colorectal carcinoma in endoscopic biopsies; additional histologic criteria for the diagnosis

In endoscopic biopsies, desmoplastic stroma and/or tumor invasion of the submucosa are generally regarded as histologic features that allow for the diagnosis of colorectal carcinoma (CRC). They are not present in all endoscopic biopsies of CRC. We investigated tumor necrosis and invasion of adjacent normal mucosa for their usefulness as possible additional histologic criteria for CRC, and evaluated quantitatively the diagnostic reliability of each of the four aforementioned histologic features in routine biopsy practice. We analyzed 440 endoscopic biopsies of lesions endoscopically suspicious of CRC and compared them with 26 colorectal adenomas with malignant change and 344 colorectal adenomas. The slides were stained by H&E and the Kreyberg-Jareg trichrome method. The endoscopic histologic diagnoses were verified by histologic examination of surgically resected specimens. In endoscopic biopsies of CRC, desmoplastic stroma was found in 83.6% of the cases, tumor necrosis in 75.7%, submucosal invasion in 27.0%, and invasion of normal mucosa in 22.7%. When only one of the diagnostic features was present, there was a false positivity of 2.5-13.3%; however, the latter has fallen to 0.8% when two features were present, but disappeared when there were three or four histologic features. Adenomas with malignant change showed necrosis in 69.2% and invasion of adjacent mucosa in 15.3%. In adenomas, necrosis was present in 0.6% of the cases, desmoplastic stroma in 3.2%, and shallow erosions in 27.3%. The presence of tumor necrosis and invasion of normal mucosa were characteristic histologic features of CRC; therefore, they represent useful additional histologic criteria for the diagnosis of CRC in endoscopic biopsies. The reliability of the histologic diagnosis of CRC correlated with the number of the four aforementioned histologic features.