Serrated colorectal polyps and polyposis

Hyperplastic polyp or sessile serrated lesion? The contribution of serial sections to reclassification

BACKGROUND

The histological discrimination of hyperplastic polyps from sessile serrated lesions can be difficult. Sessile serrated lesions and hyperplastic polyps are types of serrated polyps which confer different malignancy risks, and surveillance intervals, and are sometimes difficult to discriminate. Our aim was to reclassify previously diagnosed hyperplastic polyps as sessile serrated lesions or confirmed hyperplastic polyps, using additional serial sections.

METHODS

Clinicopathological data for all colorectal hyperplastic polyps diagnosed in 2016 and 2017 was collected. The slides were reviewed and classified as hyperplastic polyps, sessile serrated lesion, or other, using current World Health Organization criteria. Eight additional serial sections were performed for the confirmed hyperplastic polyp group and reviewed.

RESULTS

Of an initial 147 hyperplastic polyps from 93 patients, 9 (6.1%) were classified as sessile serrated lesions, 103 as hyperplastic polyps, and 35 as other. Of the 103 confirmed hyperplastic polyps, 7 (6.8%) were proximal, and 8 (7.8%) had a largest fragment size of ≥5 mm and < 10 mm. After 8 additional serial sections, 11 (10.7%) were reclassified as sessile serrated lesions. They were all less than 5 mm and represented 14.3% of proximal polyps and 10.4% of distal polyps. An average of 3.6 serial sections were required for a change in diagnosis.

CONCLUSION

Histopathological distinction between hyperplastic polyps and sessile serrated lesions remains a challenge. This study has uncovered a potential role for the use of additional serial sections in the morphological reappraisal of small hyperplastic polyps, especially when proximally located.

Mucin-rich variant of traditional serrated adenoma: a distinct morphological variant

AIMS

Traditional serrated adenomas (TSAs) account for 5% of serrated polyps, and have a villiform architecture, eosinophilic cells with a brush border, and indented, flat-topped luminal serrations. However, some are composed of mucin-filled goblet cells (GCs): mucin-rich TSA (MrTSA). The aim of this study was to determine whether this variant has unique features as compared with classic TSA (cTSA).

METHODS AND RESULTS

One hundred and fifty-six TSAs were retrieved from the period 2010-2016. Patient demographics, site of polyps and 16 microscopic variables were evaluated. TSAs containing ≥50% GCs were classified as MrTSAs. Ectopic crypt foci (ECFs) were quantified as low (1-10) or high (>10), counted at ×200 magnification, and the average was taken for 10 fields. Twenty-four fulfilled the criteria for MrTSA. In males, MrTSAs (65%) were more prevalent than cTSAs (55%). There was no age difference, and both variants had a predilection for the left colon, although, in the right colon, MrTSAs were more frequent (39%) than cTSAs (10%) (P = 0.012). Adenomatous dysplasia was present in four of 24 MrTSAs (low grade, 3; high grade, 1). The most distinctive features of MrTSAs were: a variable growth pattern [endophytic (9%), mixed (30%), or villiform/exophytic (61%)], and a lower frequency of ECFs (P = 0.001) and more intraepithelial lymphocytes (P < 0.05) than in cTSAs. MrTSAs retain characteristic luminal serrations, at least focally. Inflamed MrTSAs can mimic inflammatory polyps and hamartomatous polyps (when there are >95% GCs).

CONCLUSIONS

MrTSA is characterized by >50% GCs, and fewer ECFs than cTSA, but with preservation of archetypal luminal serrations. Awareness of this variant will prevent misdiagnosis, given the association of TSA with the accelerated pathway to colorectal cancer.

Colonic polyposis syndromes--an experience from a tertiary centre in South India

BACKGROUND

Several polyposis syndromes of the gastrointestinal tract have been recognized which carry increased risk for cancer and have a genetic predisposition. There is a paucity of literature regarding the occurrence and the burden of colonic polyposis syndromes in the Indian subcontinent. This study attempts to highlight this hitherto unaddressed burden and the associated increased risk for inherited colonic cancer in this geographical location.

METHODS

A retrospective study of various colonic polyposis syndromes encountered at a tertiary centre in South India over a period of 8 years (2005 to 2012) was performed. The diagnosis in each case was made histologically with clinicopathological correlation.

RESULTS

Fifty cases were identified as belonging to a colonic polyposis syndrome, during the study period. There were 27 males and 23 females with a median age of 36.5 years (range 19 months to 78 years). The commonest syndrome was familial adenomatous polyposis (n = 27; 54 %) followed by Peutz-Jeghers syndrome (n = 11), attenuated familial adenomatous polyposis (n = 7), juvenile polyposis syndrome (n = 3), hyperplasic polyposis syndrome (n = 1) and Cronkhite-Canada syndrome (n = 1). Colonic malignancy was documented at first presentation in 22 patients (44 %).

CONCLUSIONS

Our study highlights the various colonic polyposis syndromes encountered in a tertiary care institution in Southern India.