Pseudoinvasion in an adenomatous polyp of the colon mimicking invasive colon cancer

Chemopreventive Activity of 80% Methanol Leaf Extract of Vernonia auriculifera Hiern (Asteraceae) Against Dimethylhydrazine-Induced Colorectal Carcinogenesis in Rats

Background

Vernonia auriculifera Hiern (Asteraceae) is among Ethiopian herbal medicines that are traditionally used to treat skin and gastrointestinal cancers. In this study, the chemopreventive potential of Vernonia auriculifera leaf extract in dimethylhydrazine (DMH)-induced colorectal carcinogenesis in rats was investigated.

Methods

Rats were assigned to nine groups (normal, positive, and negative control groups, and three pre- and three post-initiation groups). Except for the normal control group (administered with 1 mL/100 g distilled water), the remaining eight groups were given DMH (20 mg/kg) intraperitoneally (ip) for 15 consecutive weeks to induce colorectal tumours. The extract was given orally to the pre-initiation and post-initiation groups at doses of 100, 200, and 400 mg/kg before and after the induction of cancer, respectively. The positive control group was treated with aspirin (60 mg/kg/day) orally for the whole experimental period. Parameters including body weight, average tumour number, size, progression, incidence, total cholesterol, serum total protein, and triglyceride levels were determined. The cytotoxic activity of the extract in Caco-2 cells was evaluated using the MTT assay, and the antioxidant activity of the extract was also assessed using 2.2-diphenyl-1-picrylhydrazine (DPPH) and reducing power methods. Moreover, total phenol and flavonoid contents were determined using appropriate methods.

Results

Rats treated with the extract showed a lower incidence of up to 50% in the pre-initiation higher dose, average number (p<0.05),and size (p<0.05) of tumours compared to untreated rats. It also inhibited colorectal cancer-associated increases in serum total cholesterol and triglycerides. The extract's IC50 value in the MTT assay was found to be higher than 200 µg/mL. The extract had an IC50 of 74.88 ± 0.86 µg/mL and 84.69 ± 2.02 µg/mL in the reducing power and DPPH assays, respectively. Total flavonoid and phenol contents were 14.51 ± 0.41 mg quercetin acid equivalent/gm and 47.37 ± 0.72 mg gallic acid equivalent/gm of the crude extract, respectively.

Conclusion

The findings collectively indicated that the leaves of V. auriculifera possess chemopreventive activity, probably mediated through antioxidant mechanisms, which supports the traditional claim.

Decrease of variation in the grading of dysplasia in colorectal adenomas with a national e-learning module

AIMS

Variation in health-care is undesirable, as this is potentially harmful for patients. In the Netherlands, an e-learning module was developed to standardise pathological evaluation of colorectal adenomas. We studied the effect of e-learning on interlaboratory variability in grading of dysplasia in screened conventional colorectal adenomas.

METHODS AND RESULTS

A cross-sectional retrospective study was performed, including all colorectal adenomas from the Dutch population-based colorectal cancer screening programme, retrieved from the Dutch Pathology Registry (PALGA) from January 2014 to July 2015. The e-learning tool, commissioned by the National Institute for Public Health, was implemented among screening pathologists from October 2014. Proportions of high-grade dysplasia (HGD) were compared before (January-July 2014) and after implementation (October 2014-July 2015) of the e-learning module. Interlaboratory variation was assessed by multilevel mixed-effects analysis. In total, 20 713 colonoscopies (20 546 patients) were performed after a positive faecal immunochemical screening test, resulting in the inclusion of 56 355 conventional adenomas from 37 pathology laboratories. Before implementation, 12 614 adenomas were diagnosed, including 4.3% with HGD. After implementation, 43 741 adenomas were diagnosed, and the HGD proportion decreased to 3.9%. Univariable analysis showed less deviant proportions of HGD after implementation in 62% of the laboratories (P = 0.019). Multilevel analysis confirmed decreased variation in the risk of diagnosing HGD (P = 0.021).

CONCLUSIONS

Interlaboratory variability in grading HGD in colorectal adenomas after a positive screening test decreased after implementation of an e-learning module for pathologists. We therefore conclude that e-learning has a favourable influence on decreasing diagnostic variability, making this a relevant strategy for health-care standardisation.

Current strategies for malignant pedunculated colorectal polyps

Despite significant advances in imaging techniques, the incidence of colorectal cancer has been increasing in recent years, with many cases still being diagnosed in advanced stages. Early detection and accurate staging remain the main factors that lead to a decrease in the cost and invasiveness of the curative techniques, significantly improving the outcome. However, the diagnosis of pedunculated early colorectal malignancy remains a current challenge. Data on the management of pedunculated cancer precursors, apart from data on nonpolypoid lesions, are still limited. An adequate technique for complete resection, which provides the best long-term outcome, is mandatory for curative intent. In this context, a discussion regarding the diagnosis of malignancy of pedunculated polyps, separate from non-pedunculated variants, is necessary. The purpose of this review is to provide a critical review of the most recent literature reporting the different features of malignant pedunculated colorectal polyps, including diagnosis and management strategies.

Diagnostic Challenges Caused by Endoscopic Biopsy of Colonic Polyps: A Systematic Evaluation of Epithelial Misplacement With Review of Problematic Polyps From the Bowel Cancer Screening Program, United Kingdom

Endoscopic mucosal biopsy may misplace mucosal elements into the submucosa of colonic adenomas, mimicking invasive adenocarcinoma. Biopsy-related misplacement can be more challenging to recognize than typical misplaced epithelium (pseudoinvasion) in pedunculated polyps. We compared the features of 16 polyps with biopsy-related misplaced epithelium with those of 10 adenomas with pseudoinvasion and 10 adenomas with invasive adenocarcinoma and performed Ki67 and p53 immunostaining on all cases. Features of misplaced epithelium in polyps referred to the Bowel Cancer Screening Program Expert Board in the United Kingdom were also evaluated for the same morphologic features. Biopsy-related epithelial misplacement occurred in adenomas throughout the colon and often appeared infiltrative (69%), including epithelial cells singly dispersed within reactive fibroinflammatory stroma or granulation tissue (44%). Misplaced epithelium displayed only low-grade cytologic features and was associated with extruded mucin (75%), tattoo pigment (63%), and misplaced normal glands (38%); scant lamina propria and muscularis mucosae were often present (88% and 44%, respectively). Cases referred to the Bowel Cancer Screening Program Expert Board also contained infiltrative-appearing misplaced epithelium (91%) that was cytologically low grade (72%), contained nondysplastic glands (11%), and showed other signs of injury. In contrast, misplaced epithelium in pedunculated polyps always had a lobular contour with a rim of lamina propria, hemorrhage, and/or hemosiderin. Invasive carcinomas showed malignant cytology and desmoplasia; most (70%) lacked features of trauma. Ki67 and p53 staining was patchy and weak in the misplaced epithelium, whereas invasive carcinomas showed increased staining for one or both markers. Pathologists should be aware that endoscopically manipulated adenomas may contain misplaced epithelium that simulates malignancy.

Malignant Colorectal Polyps; Pathological Consideration (A review)

BACKGROUND

Routine screening colonoscopy is on the rise and pathologists have to deal with the ever larger numbers of excised colonic polyps. It is very important to optimize the patients' individual treatment and further surveillance. Pathologists play a critical role in management, as most of the clinical decisions concerning colonic polyp management are based on pathologic findings. One of the most important clinical issues in colonic adenomas is the diagnosis of malignancy and reporting its different aspects by the pathologist. The histologic type and the extent of carcinoma within a malignant polyp have considerable impact on the decisions of gastroenterologists and surgeons for further management. Therefore, the most recent literature regarding the diagnosis and reporting of the different features of malignant polyps was reviewed.

DATA ACQUISITION

There is growing literature regarding the different pathologic features and reporting of malignant colonic polyps, and in this review, published articles that are listed on Google Scholar and Pub Med are discussed.

CONCLUSION

Diagnosis of malignant colon polyp requires the presence of tumor cells that are penetrating beyond the muscular mucosa into submucosa (pT1). As well as establishing a diagnosis of malignant polyp, it is very important to report the size of the invasive component, the presence or absence of lymphovascular invasion, the degree of tumor differentiation and the distance of the carcinoma from the line of resection. Other important features that may be reported include: the presence or absence of tumor budding, the depth of tumor cell penetration into the submucosa, and results of immunohistochemistry for mismatch repair proteins and BRAF.

Diagnosis of T1 colorectal cancer in pedunculated polyps in daily clinical practice: a multicenter study

T1 colorectal cancer can be mimicked by pseudo-invasion in pedunculated polyps. British guidelines are currently one of the few which recommend diagnostic confirmation of T1 colorectal cancer by a second pathologist. The aim of this study was to provide insights into the accuracy of histological diagnosis of pedunculated T1 colorectal cancer in daily clinical practice. A sample of 128 cases diagnosed as pedunculated T1 colorectal cancer between 2000 and 2014 from 10 Dutch hospitals was selected for histological review. Firstly, two Dutch expert gastrointestinal pathologists reviewed all hematoxylin-eosin stained slides. In 20 cases the diagnosis T1 colorectal cancer was not confirmed (20/128; 16%). The discordant cases were subsequently discussed with a third Dutch gastrointestinal pathologist and a consensus diagnosis was agreed. The revised diagnoses were pseudo-invasion in 10 cases (10/128; 8%), high-grade dysplasia in 4 cases (4/128; 3%), and equivocal in 6 cases (6/128; 5%). To further validate the consensus diagnosis, the discordant cases were reviewed by an independent expert pathologist from the United Kingdom. A total of 39 cases were reviewed blindly including the 20 cases with a revised diagnosis and 19 control cases where the Dutch expert panel agreed with the original reporting pathologists diagnosis. In 19 of the 20 cases with a revised diagnosis the British pathologist agreed that T1 colorectal cancer could not be confirmed. Additionally, amongst the 19 control cases the British pathologist was unable to confirm T1 colorectal cancer in a further 4 cases and was equivocal in 3 cases. In conclusion, both generalist and expert pathologists experience diagnostic difficulty distinguishing pseudo-invasion and high-grade dysplasia from T1 colorectal cancer. In order to prevent overtreatment, review of the histology of pedunculated T1 colorectal cancers by a second pathologist should be considered with discussion of these cases at a multidisciplinary meeting.

TNM staging of colorectal carcinoma: issues and caveats

The TNM staging system of the American Joint Committee on Cancer and the Union for International Cancer Control provides the most reliable guidelines for the prognostication and treatment of colorectal carcinoma. However, issues and caveats exist in the application of this system, mostly relating to the definition of the staging parameters and the pathologic interpretation of the gross and microscopic findings of the resected specimens. This article highlights some of the major issues in both areas. First, it assesses the definition of selected staging parameters, including pTis, pT4a versus pT4b, tumor deposits/N1c, ypT/ypN, and the TNM for rectal versus anal carcinoma. Second, it discusses major problematic areas in the pathologic interpretation of "pseudoinvasion" versus true invasion, deep pT2 versus superficial pT3, serosal involvement, radial margin, total mesorectal excision specimens, and postneoadjuvant chemoradiation rectal resections. The article also provides a brief discussion about some of the major adjunct histopathologic prognostic factors, such as medullary-type histology and tumor differentiation.