Mixed hyperplastic - adenomatous polyps (serrated adenomas).An intermediate step in colorectal carcinogenesis?
We compared clinicopathological characteristics of colorectal
polyps, in order to investigate the hypothesis of neoplastic
transformation of hyperplastic polyps. Of 4723
colonoscopies performed in our department over four years,
22 patients with 23 mixed hyperplastic polyps (MHAP) were
found. These were compared with 61 patients with 86 hyperplastic
polyps, 40 with 58 tubular adenomas and 27 with
35 villous adenomas. The patients of comparison groups
had exclusively one histological type of polyp. A total of 22
synchronous polypoid lesions were found in patients with
MHAP; 14 hyperplastic polyps, 6 adenomas and 2 carcinomas.
There was a remarkable similarity in the distribution
of the four histological types in the colonic regions. The
mean age of patients with hyperplastic polyps was 53.7
years, with MHAP 63.2 years (p=0.0093), with tubular adenomas
65.2 years and villous adenomas 69.5 years. Considering
the size, 87.2% of hyperplastic polyps were less
than 5 mm, while the same was true for 17.4% of MHAP,
50% of tubular and 2.9% of villous adenomas. Larger than
10 mm were 3.5%, 56.5%, 24.1% and 37.1% of the polyps
respectively. There was a significant difference (p<0.0001)
between MHAP and hyperplastic polyps in the size classifications.
In conclusion, the findings of this study further
confirm the hypothesis of a neoplastic transformation of?
hyperplastic polyps. However, the relationship between?
hyperplastic polyps? and the subsequent development of
adenomas and carcinomas remains controversial and further larger studies are warranted to evaluate the proposed
hyperplastic polyp - mixed hyperplastic adenomatous polyp
- adenoma sequence.
Keywords: Mixed hyperplastic - adenomatous polyps, serrated
adenomas, hyperplastic polyps, neoplastic transformation