Objective Sessile serrated lesions without dysplasia (SSL-ND) are epitomised by dilated crypts with epithelial serrations and architectural distortions portraying boot-shapes, L-shapes or inverted-T shapes. Recently, crypts in asymmetric fission were detected in SSL-ND. The purpose was to assess the frequency of crypts in asymmetric fission in a cohort of SSL-ND.
Methods The frequency of crypts in fission was assessed in 60 SSL-ND, the distribution of cell proliferation in 48 SSL-ND and the expression of maspin, a tumour-suppressor protein, in 29 SSL-ND.
Results Out of the 60 SSL-ND, 40 (66.7%) showed crypts in fission: 39 (65%) SSL-ND had crypts in asymmetric fission and one SSL-ND (1.7%), in symmetric fission (p<0.05). Of 1495 crypts recorded in the 60 SSL-ND, 73 (4.9%) were in asymmetric fission but only one (0.06%), in symmetric fission (p<0.05). Out of the 48 Ki67-immunostained SSL-ND,15 (31%) showed randomly distributed proliferating cell-domains. All 29 SSL-ND revealed maspin-upregulation (including crypts in asymmetric and symmetric fission). In contrast, the normal colon mucosa showed occasional single crypts in symmetric fission, proliferating cell-domains limited to the lower thirds of the crypts, absence of crypts in asymmetric fission and remained maspin negative.
Conclusions SSL-ND thrive with crypts in asymmetric fission displaying randomly distributed proliferating cell-domains and maspin-upregulation. These histo-biological aberrations disclose pathological cryptogenesis and suggest possibly unfolding somatic mutations in SSL-ND. The present findings may open new vistas on the parameters pertinent to the susceptibility of SSL-ND to develop dysplasia and carcinoma.
- morphological and microscopic findings
- pathology department
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Handling editor Runjan Chetty.
Contributors CAR reviewed all SSL-ND, collected and organised the data of the pathological findings, and wrote the original draft. PTS harvested sessile serrated lesions, obtained permission of The Regional Ethical Review Board in Stockholm, revised the original draft and introduced valuable suggestions.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This study was approved by The Regional Ethical Review Board in Stockholm (no. 2011/252-31/2 and 2018/2024-32). Since the study is retrospective and the specimens were coded and studied anonymised, The Regional Ethical Review Board in Stockholm approved the project and that consent from the patients was not needed.
Provenance and peer review Not commissioned; internally peer reviewed.
Data availability statement Data are available upon reasonable request. All data relevant to the study are included in the article. The present findings highlight a previously unreported structural histological change in sessile serrated lesions without dysplasia, namely the occurrence of asymmetric crypts in fission.