Non-adenomatous forms of gastro-oesophageal epithelial dysplasia: an under-recognised entity?

The updated WHO classification of digestive system tumours-gastric adenocarcinoma and dysplasia

The fifth edition of the World Health Organization (WHO) classification of digestive system tumours was published in 2019. The classification of invasive carcinoma is basically the same as in the fourth edition, but the description of each histological type has been updated, and some rare subtypes such as micropapillary carcinoma, gastric adenocarcinoma of the fundic gland type and undifferentiated carcinoma have been added and explained. Although this classification did not provide specific numerical criteria for the diagnosis of signet-ring cell carcinoma in poorly cohesive carcinoma, an additional study defined signet-ring cell carcinoma as having more than 90% signet-ring cells. The molecular classification of gastric cancer (Epstein-Barr virus-positive type, microsatellite instability type, genomically stable type, chromosomally unstable type) was additionally introduced. Many pages in the present classification have been devoted to precancerous lesions, and this article focuses on foveolar-type adenoma/dysplasia.

Non-conventional dysplasias of the tubular gut: a review and illustration of their histomorphological spectrum

The increasing use of gastrointestinal endoscopic procedures has led to the recognition by histopathologists of non-conventional (or special-type) dysplasias of the gastrointestinal tract. These lesions can be recognised in association with prevalent underlying gastrointestinal conditions, such as Barrett oesophagus, chronic atrophic gastritis, and inflammatory bowel disease. The diagnosis of these special types can be challenging, and their biological behaviours are not fully characterised. The aim of this review is to provide a global view of non-conventional dysplastic lesions observed in the various segments of the tubular gastrointestinal tract and describe their salient features. Furthermore, as the clinical implications of these various subtypes have not been broadly tested in practice and are not represented in most management guidelines, we offer guidance on the best management practices for these lesions.

Gastric foveolar dysplasia: a survey of reporting habits and diagnostic criteria

This study aimed to ascertain views, incidence of reporting and diagnostic criteria for gastric foveolar dysplasia. A questionnaire, a post-questionnaire discussion and microscopic assessment of selected cases was conducted by gastrointestinal pathologists to explore the above-stated aims. Fifty-four percent of respondents never or rarely diagnosed gastric foveolar-type dysplasia. The general consensus was that round nuclei, lack of nuclear stratification, presence of inflammation/damage and surface maturation favoured reactive change; while architectural abnormalities/complexity and nuclear enlargement mainly were used to separate low-grade from high-grade foveolar dysplasia. Immunohistochemistry was rarely used to make the diagnosis of dysplasia and was thought not to be of help in routine practice. Inter-observer agreement in grading of dysplasia versus reactive, and the type of dysplasia (foveolar versus adenomatous), was substantial/almost perfect amongst 35.7% and 21.4% of participants, respectively. This reflects low reproducibility in making these diagnoses. In conclusion, foveolar dysplasia was a rarely made diagnosis among 14 gastrointestinal pathologists, there are no uniform criteria for diagnosis and there is poor inter-observer agreement in separating low-grade foveolar dysplasia from reactive gastric mucosa and low-grade adenomatous dysplasia. Greater awareness and agreed criteria will prevent misdiagnosis of low-grade foveolar dysplasia as reactive, and vice versa.