| Theme | Serrated polyp of the colon, including large hyperplastic polyp | |
|---|---|---|
| Title | Clinicopathological characteristics of serrated adenomas of the large intestine | |
| Publish Date | 2006/07 | |
| Author | Seiji Haraoka | Department of Pathology, Chikushi Hospital, Fukuoka University |
| Author | Akinori Iwashita | Department of Pathology, Chikushi Hospital, Fukuoka University |
| [ Summary ] | Clinicopathological study of serrated adenoma (SA) of the large intestine was carried out in 1,018 specimens consisting of 526 polypectomy specimens, 33 surgically resected specimens and 459 biopsy specimens. The results obtained were as follows : (1) The average age was 62.6 years and the male to female ratio was 1.7 : 1. SA was most frequently observed in the rectosigmoid colon (615 of 1,018 lesions). (2) The macroscopic findings of SA were classified as : sessile (66.6 %), pedunculated (26.5 %) and subpedunculated (6.9 %) elevated lesions. No SA of depressed type was noted. The average largest diameter was 9.1 ± 4.5 mm, ranging from 2 to 25 mm. Seventy three percent of the lesions were small, measuring 2 to 10 mm. Endoscopically, seventy three percent of SA had reddish surface color. (3) Serrated adenomas studied were histologically classified into two groups as follows : SA without traditional adenomatous component (TAC) (669 lesions) and SA with TAC (349 lesions). According to the manner of distribution of SA and TA components, the latter was divided into thee subtypes as follows : mixed type, separate type, and mixed + separate type. (4) The average largest diameter was larger in SA with TAC than in SA without TAC, and the lesions of pedunculated type were more frequently found in SA without TAC than in SA with TAC, with statistically significant difference. (5) Three hundred eighty three of the 1,018 lesions (37.6 %) had component of hyperplastic polyp. Statistically, the incidence was significantly higher in SA without TAC (50.8 %) then in SA with TAC (12.3 %). (6) Histologically, 72.8 % of SA showed mild atypia, and 26.5 % of SA revealed moderate atypia. The incidence of SA with mild atypia was greater in SA without TAC than in SA with TAC. (7) Mucus producing cells including goblet cells with various degrees of differentiation were recognized in all lesions, but neoplastic Paneth cells were not found in all SA. (8) Only twenty (1.96 %) of the SA contained the foci of intramucosal well differentiated adenocarcinoma. The average largest diameter was 16.45 mm, and the atypia of the SA was moderate in 19 lesions and severe in one lesion. The incidence of SA with carcinoma component was greater in SA with TAC (3.4 %) than in SA without TAC (1.2 %), with statistically significant difference. In conclusion, it was shown that serrated adenoma of the large intestine are histologically classified into two groups, and has a lower malignant potential than traditional adenoma. The serrated adenoma may reflect a neoplastic transformation of the epithelial cells in hyperplastic polyp. |
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