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Microsatellite instability is found in 15% of sporadic colorectal cancers (CRC) and 95% of hereditary CRC cases. Lynch syndrome (LS) diagnosis begins with the analysis of the surgical specimen using methods such as immunohistochemistry (IHC), which identifies changes in the nuclear expression of DNA mismatch repair (MMR) proteins. However, IHC analysis on endoscopic biopsies could provide substantial benefits. Our goal was to assess the accuracy of MMR IHC status on endoscopic biopsies in comparison to corresponding surgical specimen in a series of CRC. We retrospectively selected patients who had undergone CRC surgery between February 2011 and January 2020 and had IHC testing for MMR proteins on the surgical specimen. The study was then performed on the corresponding endoscopic biopsies and results were compared. MMR IHC staining on surgical specimens were available for 361 CRC patients and only in 154 cases for preoperative endoscopic biopsies. The concordance between MMR IHC status of the endoscopic biopsy and the surgical specimen analysis was 98.6% for the MLH1/PMS2 proteins and 100% for MSH2/MSH6. In conclusion, endoscopic biopsies of colorectal tumors serve as a suitable tissue source for the immunohistochemical analysis of DNA repair proteins. The correlation with results from the surgical specimen was notably high and discrepancies were primarily as a result of intratumoral heterogeneity within the same sample. The features of MMR protein loss in endoscopic biopsies can provide clinicians with valuable information for specific therapeutic approaches and genetic counseling.

A 69-year-old woman from a kindred with familial atypical multiple mole melanoma and carrier of a germline mutation in CDKN2A , presented with abdominal pain caused by a solid-cystic pancreatic mass. The patient had an abdominal computed tomography three years before in which there was no evidence of pancreatic lesion. The endoscopic ultrasound guided fine needle aspiration showed adenocarcinoma with squamous component. After surgical resection the final diagnosis was adenosquamous pancreatic carcinoma (ASPC) arising in an intraductal papillar mucinous neoplasm (IPMN). Adenosquamous carcinomas are uncommon in the pancreas and have rarely been described in association with IPMNs. It has worse prognosis than the ordinary pancreatic ductal adenocarcinoma and some distinct features. We review the clinical, imaging, pathologic and molecular aspects of ASPC. Differential diagnosis with contamination, squamous metaplasia and pancreatic metastases from a distant squamous carcinoma is discussed. Besides, the case is an accelerated model of the adenoma (IPMN)-carcinoma sequence probably due to the CDKN2A germline mutation. Somatic CDKN2A mutations are common events in the early steps of sporadic pancreatic cancer, but germline mutation carriers have a significantly higher risk of pancreatic carcinoma., Competing Interests: Conflict-of-interest statement: The authors declare non conflict of interest.

We describe a new case of enteropathy with villous atrophy in a patient suffering from arterial hypertension treated with olmesartan. The molecular and serological studies showed anti-nuclear antibodies (ANA) and haplotype HLA-DQ2 positive, as well as negative results for anti-transglutaminase, anti-endomysium and anti-enterocytes antibodies. A duodenal villous atrophy was suspected by upper gastrointestinal endoscopy, which was confirmed by histopathology. The morphological picture was suggestive of sprue-like enteropathy with severe lymphoid infiltration and predominant T lymphoid cells.