Serrated and microtubular colorectal adenomas in Italian patients. A 5-year survey.

Colorectal adenomas from 1552 Italian patients were histologically classified into tubular (TAs), tubulo-villous (TVAs), villous (VAs), serrated (SAs) and microtubular (MTAs). The purpose was to compare the results to those in 3135 colorectal adenomas from Swedish patients. Of the 1552 adenomas, 827 (53%) were TAs, 352 (23%) TVAs, 196 (12%) VAs, 102 (7%), SAs and 14 (0.9%) MTAs. The remaining 61 (4%) were of combined phenotypes (COMBAs). The percentage of VA (considered as the most important dysplastic precursor of colorectal cancer) was higher in Florence than in Stockholm. Notably, the incidence of colorectal cancer in males was also higher in Florence (78.6/10(5)) than in Stockholm (57.2/10(5)). Notwithstanding, the highest rate of submucosal invasion (7%) was found among SAs. The diameter of the largest section was used to define the size of the largest adenoma in individual patients. Of the 1380 neoplasias measuring < or =12 mm, only 0.9% (n=13) had invasive carcinomas, but as many as 8.1% (n=14) of the 172 neoplasias measuring > or =13 mm. SAs and MTAs are special adenoma phenotypes with particular morphological and cell proliferative attributes at variance from those of TAs, VAs or TVAs. In the light of the present results, it is proposed that SAs and MTAs are included in future reports of colorectal adenomas in order to compare their frequency worldwide.