Background and purpose: Colorectal cancer is one of the most common types of cancers worldwide. Most of the times it is superimposed on an adenomatous polyp. Today, colonoscopy is the gold standard screening test for diagnosis of colorectal cancer which prevents developing cancer on the adenocarcinoma sequence path way. The goal of this study was to evaluate the gross and microscopic characteristics and the type of colonic polyps.

Materials and methods: A descriptive cross-sectional study was performed using the information available in pathology department in Sari Imam Khomeini Hospital, 2004-2014. Data including age, gender, site of polyp, size and histologic type was recorded.

Results: There were 548 polyps of which 56.7% were seen in male patients. The patients were between 14 to 88 years of age. More than half of the polyps were found in those aged 50 to 70 years of old, but 15.1% were observed in cases under 40 years of age. 54.8% of the polyps were located in rectosigmoid and 16.5% were found in left part of the colon before splenic flexure. Histologic studies revealed different types of polyps including adenomatous (57.6%), hyperplastic (16.4%), juvenile (6%), retention (5.8%), adenocarcinoma (4%), high grade dysplasia (3.9%), no polyp (3.3%), and mixed hyperplastic adenomatous polyps (3.2%). Among adenomatous polyp, there were tubular (83.1%), tubulovillous (16.3%), and villous (2.4%) adenomas.

Conclusion: Adenomatous polyp, especially tubular adenoma was the most common colonic polyp and it was more common in rectosigmoid area among male patients aged 50-70 years old.