The introperative consultation for colectomy here is mostly gross examination: is the tumor present at proximal and distal margins? How far? Grossly, does the tumor invade into muscularis propria and how deep?   Diagnosis is done before colectomy.  Occasionally we do frozen sections to determine if the the serosal surface is involved.  Touch prep is a good way to learn cytologic diagnosis of tumors.  We used to do FNA and touch preps in frozen section room using resected hepatic tumors,  lung tumors, renal tumors.... just to learn cytologic features.  When GI doctors or radiologists request immediate interpretations during FNA, we can provide fast and reliable diagnoses.

The above touch prep photomicrographs look like adenocarcinoma.  Please note that the accurate diagnosis of colonic adenocarcinoma is based on where the malignant glands invade into, not only based on cytologic features.  For example, high grade dysplasia (adenocarcinoma in situ) and invasive adenocarcinoma can have exactly the same degree of cytoatypia.  The invasive is invasive only because the malignant glands invade at least into submucosa while in situ doesn't invade at all, not even into lamina propria.