The Day-To-Day Practice of MMR and MSI Assessment in Colorectal Adenocarcinoma: What We Know and What We Still Need to Explore.

BACKGROUND: The DNA mismatch repair (MMR) system is a highly preserved protein complex recognizing short insertions, short deletions, and single base mismatches during DNA replication and recombination. MMR protein status is identified using immunohistochemistry. Deficit in one or more MMR proteins, configuring deficient MMR status (dMMR), leads to frameshift mutations particularly clustered in microsatellite repeats. Thus, microsatellite instability (MSI) is the epiphenomenon of dMMR. In colorectal cancer (CRC), MMR/MSI status is a biomarker with prognostic and predictive value of resistance to 5-fluorouracil and response to immune checkpoint inhibitor therapy. SUMMARY: In this Review, we describe the challenges the practicing pathologist may face in relation to the assessment of MMR/MSI status and any open issues which still need to be addressed, focusing on pre-analytic issues, pitfalls in the interpretation, and technical aspects of the different assays. KEY MESSAGES: The current methods of detecting dMMR/MSI status have been optimized for CRCs, and whether these techniques can be applied to all tumor and specimen types is still not fully understood. Following the Food and Drug Administration (FDA), tissue/site agnostic drug approval of pembrolizumab for advanced/metastatic MSI tumors, MMR/MSI status in gastrointestinal tract is a common request from the oncologist. In this setting, several issues still need to be addressed, including criteria for sample adequacy.

hERG1 Potassium Channel Expression in Colorectal Adenomas: Comparison with Other Preneoplastic Lesions of the Gastrointestinal Tract.

Preneoplastic lesions represent a useful target for early diagnosis and follow-up of gastrointestinal malignancies. hERG1 channel expression was tested by immunohistochemistry (IHC) in a cohort of colorectal adenoma samples belonging to Italian subjects. Overall, hERG1 was expressed in 56.5% of cases with both high staining intensity and a high percentage of positive cells. Moreover, hERG1 was expressed in a higher percentage of dysplastic adenomas with respect to hyperplastic lesions, and the proportion of positive samples further increased in patients with high-grade dysplasia. Comparing hERG1 expression in other preneoplastic lesions of the GI tract (gastric dysplasia and Barrett's esophagus), it emerged that in all the conditions, hERG1 was expressed with a diffused pattern, throughout the cell, with variable staining intensity within the samples. The highest expression was detected in gastric dysplasia samples and the lowest in Barrett's esophagus at similar levels observed in colorectal adenomas. Our results show that hERG1 is aberrantly expressed in human preneoplastic lesions of the gastrointestinal tract and has a different pattern of expression and role in the different sites. Overall, the detection of hERG1 expression in preneoplastic lesions could represent a novel diagnostic or prognostic marker of progression in the gastrointestinal tract.

Molecular Alterations in Gastric Preneoplastic Lesions and Early Gastric Cancer.

Prognosis of gastric cancer is dramatically improved by early diagnosis. Correa's cascade correlates the expression of some molecular markers with the progression of preneoplastic lesions toward carcinoma. This article reviews the diagnostic and prognostic values of molecular markers in complete (MUC2) and incomplete (MUC2, MUC5AC, and MUC6) intestinal metaplasia, gastric dysplasia/intra-epithelial neoplasia, and early gastric cancer. In particular, considering preinvasive neoplasia and early gastric cancer, some studies have demonstrated a correlation between molecular alterations and prognosis, for example, mucins phenotype in gastric dysplasia, and GATA6, TP53 mutation/LOH and MUC6 in early gastric cancer. Moreover, this review considers novelties from the literature regarding the (immuno)histochemical characterization of diffuse-type/signet ring cell gastric cancer, with particular attention to clinical outcomes of patients. The aim of this review is the evaluation of the state of the art regarding suitable biomarkers used in the pre-surgical phase, which can distinguish patients with different prognoses and help decide the best therapeutic strategy.

Histopathology of IBD Colitis. A practical approach from the pathologists of the Italian Group for the study of the gastrointestinal tract (GIPAD).

Inflammatory bowel diseases (IBDs) are lifelong disorders in which an interaction between genetic and environmental factors is involved. IBDs include two entities: Crohn's disease (CD) and ulcerative colitis (UC); these can be adequately diagnosed and distinguished with a correct methodological approach based on communicating exhaustive clinical, endoscopic and laboratory information to the pathologist and performing adequate bioptic sampling and precise morphological signs including crypt architecture, distribution of inflammation and granulomas, when present. IBD needs to be distinguished from non-IBD colitis, mostly at its onset. Moreover, IBDs are associated with an increased risk of developing colorectal adenocarcinoma. In daily pathological practice, correct diagnosis of IBD and its subclassification as well as a correct detection of dysplasia is imperative to establish the best therapeutic approach.

Gastro-esophageal reflux disease and Barrett's esophagus: an overview with an histologic diagnostic approach.

The first part of this overview on non-neoplastic esophagus is focused on gastro-esophageal reflux disease (GERD) and Barrett's esophagus. In the last 20 years much has changed in histological approach to biopsies of patients with gastro-esophageal reflux disease. In particular, elementary histologic lesions have been well defined and modality of evaluation and grade are detailed, their sensitivity and specificity has been evaluated and their use has been validated by several authors. Also if there is not a clinical indication to perform biopsies in patient with GERD, the diagnosis of microscopic esophagitis, when biopsies are provided, can be performed by following simple rules for evaluation which allow pathologists to make the diagnosis with confidence. On the other hand, biopsies are required for the diagnosis of Barrett's esophagus. This diagnosis is the synthesis of endoscopic picture (which has to be provided with the proper description on extent and with adequate biopsies number) and histologic pattern. The current guidelines and expert opinions for the correct management of these diagnosis are detailed.

Non gastro-esophageal reflux disease related esophagitis: an overview with a histologic diagnostic approach.

Several pathological conditions, other than gastro-esophageal reflux disease and its complications, can affect the esophagus. While some of these can present with unspecific lesions (i.e. ulcers and epithelial damage) and require clinico-pathological correlation for diagnosis (i.e. drug-induced esophagitis and corrosive esophagitis) other conditions show distinctive histological lesions which enable the pathologist to reach the diagnosis (i.e. some specific infectious esophagites and Crohn's disease). In this context eosinophilic esophagitis is the condition which has been increasingly studied in the last two decades, while lymphocytic esophagitis, a relatively new entity, still represents an enigma. This overview will focus on and describe histologic lesions which allow pathologists to differentiate between these conditions.

Gastro-intestinal metastasis from Melanoma: Clinico-pathological clues.

INTRODUCTION: Metastasis from melanoma in the gastro-intestinal tract is a frequent event but, in the absence of an adequate clinical context and oncological anamnesis, it could be misdiagnosed by the pathologists. Moreover, amelanotic and/or poorly differentiated metastasis from melanoma in the gastro-intestinal tract can be easily underestimated. MATERIALS AND METHODS: We describe the histological features of gastro-intestinal metastasis from melanoma in a multi-centric cohort of 49 patients. In 24/49 patients, we were able to compare histological findings such as the growth pattern and the melanotic pigment also in the primary melanoma. RESULTS: The epithelioid pattern is the most common growth pattern observed in gastro-intestinal metastasis (57 %), followed by the mixed pattern (41 %) and the spindled pattern (2 %). We documented a discordant growth pattern between metastasis and primary in 9/24 cases and the absence of melanotic pigment in 8/49 cases. DISCUSSION: Our experience highlights that pathologists should take into account the possibility of gastro-intestinal metastasis from melanoma also in cases with spindled-cells/amelanotic lesions, without a previous anamnesis of melanoma asportation, and in cases of a discordant growth pattern with the primary. A correct clinical integration and an aware immunohistochemical approach are imperative to best manage the bioptic sample in order to investigate the biological profiling and therefore plan a personalizated therapy.

Cytomegalovirus-Related Gastritis in an Immunocompetent Host Presenting With Infectious Gastroparesis.

Cytomegalovirus (CMV) infection is usually asymptomatic or causes a mild mononucleosis-like syndrome, whereas severe symptoms are rarely reported. We report a case of a 70-year-old woman who was admitted to our center because of severe clinical presentation with anorexia, epigastric pain, nausea, postprandial vomiting, and significant weight loss. Esophagogastroduodenoscopy with biopsies showed ulcerative chronic gastritis with scattered large cells with inclusion bodies. Immunohistochemistry and polymerase chain reaction for CMV-DNA resulted positive. A gastric emptying of solid scintigraphy showed severe gastroparesis. The patient was discharged after 2 months of antiviral therapy completely asymptomatic. To the best of our knowledge, this is the first case of CMV-related gastroparesis in an immunocompetent patient, successfully treated with antiviral therapy.

HER2-low in gastro-oesophageal adenocarcinoma: a real-world pathological perspective.

AIMS: In the DESTINY-Gastric01 trial, a novel HER2-targeted antibody-drug conjugate trastuzumab deruxtecan proved to be effective in HER2-low gastro-oesophageal adenocarcinomas. The aim of our study is to investigate the clinicopathological and molecular features of HER2-low gastric/gastro-oesophageal junction cancers in the real-world setting of a large multi-Institutional series. METHODS: We retrospectively evaluated 1210 formalin-fixed paraffin-embedded samples of gastro-oesophageal adenocarcinomas which were analysed by immunohistochemistry for HER2 protein expression in 8 Italian surgical pathology units from January 2018 to June 2022. We assessed the prevalence of HER2-low (ie, HER2 1+ and HER2 2+ without amplification) and its correlation with clinical and histopathological features, other biomarkers' status, including mismatch repair/microsatellite instability status, Epstein-Barr encoding region (EBER) and PD-L1 Combined Positive Score. RESULTS: HER2 status could be assessed in 1189/1210 cases, including 710 HER2 0 cases, 217 HER2 1+, 120 not amplified HER2 2+, 41 amplified HER2 2+ and 101 HER2 3+. The estimated prevalence of HER2-low was 28.3% (95% CI 25.8% to 31.0%) overall, and was higher in biopsy specimens (34.9%, 95% CI 31.2% to 38.8%) compared with surgical resection specimens (21.0%, 95% CI 17.7% to 24.6%) (p<0.0001). Moreover, HER2-low prevalence ranged from 19.1% to 40.6% among centres (p=0.0005). CONCLUSIONS: This work shows how the expansion of the HER2 spectrum might raise problems in reproducibility, especially in biopsy specimens, decreasing interlaboratory and interobserver concordance. If controlled trials confirm the promising activity of novel anti-HER2 agents in HER2-low gastro-oesophageal cancers, a shift in the interpretation of HER2 status may need to be pursued.

Efficacy and Safety of a Novel Triple-anchoring Technique for Colonic Hybrid Endoscopic Mucosal Resection: A Case Series.

BACKGROUND AND AIMS: A hybrid technique may be a reasonable compromise to make endoscopic mucosal resection (EMR) more reliable for lesions ≥ 20 mm and a good way of approaching to endoscopic submucosal dissection (ESD). The aim of this study was to assess the efficacy and safety of a novel hybrid EMR technique, triple-anchoring EMR (T-EMR) for colorectal lesions 20-30 mm. METHODS: Fifteen patients have been prospectively enrolled to T-EMR from December 2019 to April 2020 in two Endoscopy Units: Policlinico A. Gemelli, Rome, and University Hospital of Udine, Italy. Patients eligible for the study were ≥18 years old with superficial colorectal lesions 20-30 mm, morphologically liable to endoscopic treatment based on chromoendoscopy. The primary endpoint was assessment of the "en bloc" and the free resection margins (R0) rates. The secondary endpoints were resected specimen size, procedure time, complication rate, and recurrence rate at 6 months. RESULTS: Among the 15 patients enrolled, 12 were males (80%), mean age 68.73±11.04 years. The mean size of the lesions was 24.93±2.89 mm. Mean procedure time was 22.13±4.31 min. T-EMR was performed en bloc in 14/15 patients (93.3%) with R0 in 13/15 patients (86.7%). No major intra-/peri-procedural or delayed complications occurred. At histological analysis, 13/15 lesions (86.7%) were adenomas, while 2 were early colorectal cancer. At a 6-month follow-up colonoscopy, only one patient (6.7%) had a recurrence of adenoma. CONCLUSIONS: T-EMR seems to be an effective and safe option to treat colorectal lesions between 20 and 30 mm, with a short procedure time and low costs.

An Incidental Uptake of 18F-Choline at PET/CT in Gastric Neuroendocrine Tumor.

ABSTRACT: We present a case of neuroendocrine tumor localized in the gastric mucosa, incidentally detected by 18F-choline PET/CT in a 69-year-old man with prostate cancer. 18F-choline PET/CT scan showed an increased activity in the stomach, later diagnosed as a well-differentiated neuroendocrine tumor, at biopsy. A careful attention of reading 18F-choline PET/CT images should be made, in order to avoid the missing of potential concomitant neoplasia in patients with prostate cancer.

Histopathology of inflammatory bowel disease - Position statement of the Pathologists of the Italian Group for the Study of Inflammatory Bowel Disease (IG-IBD) and Italian Group of Gastrointestinal Pathologists (GIPAD-SIAPEC).

Diagnosis of the inflammatory bowel diseases ulcerative colitis (UC) and Crohn's disease (CD) relies mainly on the histopathological examination of endoscopic biopsies of the gastrointestinal tract. To facilitate the accurate diagnosis of these two conditions, this paper addresses key issues on the: (A) gastrointestinal biopsy procedure, (B) histomorphological characteristics of UC and CD, and (C) diagnosis of dysplasia. The 13 statements presented here represent the consensus of two groups of Italian pathologists (IG-IBD and GIPAD).

Role of magnified ileoscopy in the diagnosis of cases of coeliac disease with predominant abdominal symptoms.

OBJECTIVE: Less severe histological changes have sometimes been reported in the terminal ileum (TI) of coeliac patients. The aim of this work was to assess whether magnified ileoscopy and the corresponding biopsy could be used when diagnosing coeliac disease (CD). This would be of clinical value in coeliac patients who show predominant abdominal symptoms and who undergo colonoscopy with ileoscopy as first clinical examination. MATERIAL AND METHODS: All patients underwent conventional and magnified ileoscopy, along with histological examination of macroscopic mucosal abnormalities, if present. Patients whose ileoscopy with biopsy suggested CD underwent a blood test for quantitative determination of anti-transglutaminase antibodies and upper gastrointestinal endoscopy with corresponding duodenal biopsy. RESULTS: Out of 143 patients enrolled, 21 had a TI mucosal lesion, and 10 of these showed villous atrophy at ileoscopy only after magnification. Six showed a count of intra-epithelial lymphocytes (IELs) >25/100 enterocytes and upper intestinal lesions, confirming the diagnosis of CD. Finally, of four patients diagnosed with Crohn's disease, TI mucosal aftoid lesions were seen in two only in magnified view. CONCLUSIONS: Magnified ileoscopy reliably recognizes the presence of mucosal villous subtotal or total atrophy at TI. This finding, even if not specific to CD, can address the diagnosis of CD. Magnification in the course of ileoscopy could also be useful in the diagnosis of Crohn's disease.

The modern treatment of early gastric cancer: our experience in an Italian cohort.

BACKGROUND: Endoscopic submucosal dissection (ESD) has been developed as treatment for early gastric cancer (EGC) by Japanese authors. However, there are no reports about its possible implementation in the Western setting. The aim of the present work is to determine the safety and efficacy of the endoscopic treatments for EGC in an Italian cohort. METHODS: Forty-five patients for a total of 48 gastric lesions were enrolled in the study. Thirty-six EMR procedures were performed with the strip biopsy technique using a double-channel endoscope. En bloc resection refers to resection in one piece, while piecemeal refers to resections in which the lesion was removed in multiple fragments. A total of 12 ESD were performed and completed with IT knife. We define as curative treatment lateral and vertical margins of the resected specimens free of cancer and repeat endoscopic finding of no recurrent disease. RESULTS: Out of 36 EMR procedures, 10 were piecemeal resections (28%), while 26 were en bloc (72%). ESD led to en bloc resection in 11/12 cases (92%). Histological assessment of curability in the EMR group was achieved in 56% of the cases, and in 92% of the ESD group. Mean follow-up period was 31 months (range: 12-71 months). There was no local recurrence or distant metastasis in the curative group patients. CONCLUSIONS: These results seem to confirm the safety and the clinical efficacy of the ESD procedure in the Western world too.

Squamous cell carcinoma of the breast. Report of two cases.

Squamous Cell Carcinoma (SCC) of the breast is a rare entity, not well known, nevertheless literature reports several signalings from different authors. Regarding ethiopathogenesis, SCC of the breast is still the object of numerous discordances and controversies. We report two cases of SCC of the breast referred to our institution in the last year. The first case interests a 35 years-old woman with a lesion of the left breast referred to us with a 3 month history of breast mass. The second case regards a 49 year-old women with multicentric lesions of the right breast operated in two different times. The SCC is a rare breast entity with a controversial histogenesis. The development is characterized by metastasis frequency. The treatment remains not codified. The treatment is currently the same as for infiltrating ductal carcinoma. Indeed, the limited number of this kind of tumor doesn't allow the assessment of different therapeutic protocols.

A case of primary pancreatic non-Hodgkin B-cell lymphoma mimicking autoimmune pancreatitis.

Non Hodgkin lymphoma frequently involves the gastrointestinal tract, in particular the stomach and the small bowel. Rarely, it can also be a cause of pancreatic masses. Clinical presentation is often non-specific and may overlap with other pancreatic conditions such as carcinoma, neuroendocrine tumours and autoimmune pancreatitis. We report a case of primary pancreatic lymphoma in a young woman with jaundice, fever and abdominal pain mimicking autoimmune pancreatitis. Clinical evaluation included the abdominal Computed Tomography scan, Magnetic Resonance Imaging and an upper gastrointestinal endoscopy that revealed a large duodenal mass. Endoscopic biopsies were performed and eventually histological examination was coherent with a diagnosis of primary pancreatic lymphoma.

Neoadjuvant Chemoradiotherapy with Volumetric-modulated Arc Therapy for Medium-distal Oesophageal and Gastro-oesophageal Junction Carcinoma.

AIM: to appraise the role of volumetric-modulated arc therapy (VMAT) in the neoadjuvant chemoradiotherapy management of advanced medium and distal oesophageal cancer in terms of toxicity and response to treatment. PATIENTS AND METHODS: Thirty patients were treated according to the neoadjuvant chemoradiation followed by surgery versus surgery-alone trial scheme with VMAT radiation therapy. Patients presented mainly T3-T4 stage (80%) and N1-2 (96.6%) disease. The chemotherapy scheme consisted of 3-5 cycles, while a radiotherapy course of 41.4 Gy in 23 fractions was administered to all patients. RESULTS: The median age of patients was 65 years, and there was a predominance of males (80%), smokers or ex-smokers (90%) and modest alcohol habit (80% negative). Primary tumor localisation was in the medium and distal third of the oesophagus in 57% of the cases, the rest being in the gastro-oesophageal junction. Modest toxicity profiles were observed, with limited incidence of grade 2-3 events. Partial or complete response was observed in more than 90% of the cases (radiological/metabolic) and was confirmed after surgical intervention (67% partial or complete and 27% stable response). Tumor down-staging was recorded in 67% of patients and nodal down-staging in 50%. CONCLUSION: VMAT was applied in the context of neoadjuvant chemoradiotherapy for the treatment of medium and distal oesophageal carcinoma with satisfactory results in terms of tolerance and toxicity.