Number of intraepithelial lymphocytes and presence of a subepithelial band in normal colonic mucosa differs according to stainings and evaluation method.

Chronic watery diarrhea is a frequent symptom. In approximately 10% of the patients, a diagnosis of microscopic colitis (MC) is established. The diagnosis relies on specific, but sometimes subtle, histopathological findings. As the histology of normal intestinal mucosa vary, discriminating subtle features of MC from normal tissue can be challenging and therefore auxiliary stainings are increasingly used. The aim of this study was to determine the variance in number of intraepithelial lymphocytes (IELs) and presence of a subepithelial band in normal ileum and colonic mucosa, according to different stains and digital assessment. Sixty-one patients without diarrhea referred to screening colonoscopy due to a positive feacal blood test and presenting with endoscopically normal mucosa were included. Basic histological features, number of IELs, and thickness of a subepithelial band was manually evaluated and a deep learning-based algorithm was developed to digitally determine the number of IELs in each of the two compartments; surface epithelium and cryptal epithelium, and the density of lymphocytes in the lamina propria compartment. The number of IELs was significantly higher on CD3-stained slides compared with slides stained with Hematoxylin-and-Eosin (HE) (p<0.001), and even higher numbers were reached using digital analysis. No significant difference between right and left colon in IELs or density of CD3-positive lymphocytes in lamina propria was found. No subepithelial band was present in HE-stained slides while a thin band was visualized on special stains. Conclusively, in this cohort of prospectively collected ileum and colonic biopsies from asymptomatic patients, the range of IELs and detection of a subepithelial collagenous band varied depending on the stain and method used for assessment. As assessment of biopsies from patients with diarrhea constitute a considerable workload in the pathology departments digital image analysis is highly desired. Knowledge provided by the present study highlight important differences that should be considered before introducing this method in the clinic.

Digitally assessed lymphocyte infiltration in rectal cancer biopsies is associated with pathological response to neoadjuvant therapy.

A frequently used treatment strategy in locally advanced rectal cancer (RC) is neoadjuvant therapy followed by surgery. Patients treated with neoadjuvant therapy achieve varying pathological response, and currently, predicting the degree of response is challenging. This study examined the association between digitally assessed histopathological features in the diagnostic biopsies and pathological response to neoadjuvant therapy, aiming to find potential predictive biomarkers. 50 patients with RC treated with neoadjuvant chemotherapy and/or radiotherapy followed by surgery were included. Deep learning-based digital algorithms were used to assess the epithelium tumor area percentage (ETP) based on H&E-stained slides, and to quantify the density of CD3+ and CD8+ lymphocytes, as well as the CD8+/CD3+ lymphocyte percentage, based on immunohistochemically stained slides, from the diagnostic tumor biopsies. Pathological response was assessed according to the Mandard method. A good pathological response was defined as tumor regression grade (TRG) 1-2, and a complete pathological response was defined as Mandard TRG 1. Associations between the ETP and lymphocyte densities in the diagnostic biopsies and the pathological response were examined. The density of CD8+ lymphocytes, and the CD8+/CD3+ lymphocyte percentage, were associated with both good and complete response to neoadjuvant therapy, while the density of CD3+ lymphocytes was associated with complete response. The ETP did not correlate with response to neoadjuvant therapy. It is well-known that infiltration of lymphocytes in colorectal cancer is a prognostic biomarker. However, assessment of CD8+ and CD3+ lymphocytes in the diagnostic tumor biopsies of patients with RC may also be useful in predicting response to neoadjuvant therapy.

Deeper sections reveal residual tumor cells in rectal cancer specimens diagnosed with pathological complete response following neoadjuvant treatment.

Guidelines and requirements for diagnosing pathological complete response (pCR) in rectal adenocarcinoma following neoadjuvant treatment vary, and there is currently no consensus on the appropriate number of sections to examine per formalin-fixed, paraffin-embedded (FFPE) tissue block. The consequences of systematic use of deeper sections on the diagnostic accuracy and prognosis for patients classified as ypT0 rectal cancer were investigated. In this retrospective study, 23 out of 155 patients who underwent neoadjuvant therapy and surgical resection between 2015 and 2020 were diagnosed with ypT0 rectal cancer. Three additional deeper sections were cut from each FFPE block from the primary tumor site and reviewed for presence of residual tumor cells. Additional sections revealed residual viable tumor cells in seven patients (30.4%), reducing the rate of pCR in the cohort from 14.8 to 10.3%. Of the seven patients, three patients later had local recurrence or distant metastasis during the follow-up period, compared with one patient with no residual tumor cells in deeper sections (p = 0.07). A nonsignificant reduction in disease-free survival (p = 0.08) was observed in the patients with residual tumor. Systematic use of deeper sections in evaluation of tumor regression in rectal cancer reveals the presence of residual tumor cells in a subset of patients originally diagnosed with pCR based on a single section per FFPE block. Although the results are not statistically significant, it cannot be excluded that accurately distinguishing complete from near-complete response may be clinically relevant for prognostic prediction.

Development of a method for digital assessment of tumor regression grade in patients with rectal cancer following neoadjuvant therapy.

Neoadjuvant chemo-radiotherapy (nCRT) followed by surgical resection is the standard treatment strategy in patients with locally advanced rectal cancer (RC). The pathological effect of nCRT is assessed by determining the tumor regression grade (TRG) of the resected tumor. Various methods exist for assessing TRG and all are performed manually by the pathologist with an accompanying risk of interobserver variation. Automated digital image analysis could be a more objective and reproducible approach to evaluate TRG. This study aimed at developing a digital method to assess TRG in RC following nCRT, and correlate the results to the currently used Mandard method. A deep learning-based semi-automatic Epithelium-Tumor area Percentage (ETP) algorithm enabling quantification of tumor regression by determining the percentage of residual tumor epithelium out of the total tumor area was developed. The ETP was quantified in 50 cases treated with nCRT and 25 cases with no prior nCRT served as controls. Median ETP was 39.25% in untreated compared with 6.64% in patients who received nCRT (P < .001). The ETP of the resected tumors treated with nCRT increased along with increasing Mandard grade (P < .001). As new treatment strategies in RC are emerging, performing an accurate and reproducible evaluation of TRG is important in the assessment of treatment response and prognosis. TRG is often used as an outcome point in clinical trials. The ETP algorithm is capable of performing a precise and objective value of tumor regression.

Hepatic pinworm infestation misdiagnosed as a liver metastasis in a patient with colonic adenocarcinoma.

An extra-intestinal infestation of Enterobius vermicularis (pinworm) is uncommon. We present a case of hepatic infestation of pinworm in a 57-year-old woman, misdiagnosed as a colorectal adenocarcinoma metastasis. The route of migration from the intestine to the liver is not well established but the most plausible route seems to be hematogenous. In concordance with previously published cases, the hepatic pinworm infestation is usually localised superficially in the right liver lobe. Hence solitary lesions in this location detected radiologically should be interpreted carefully. Additionally, the serum CEA level could be useful to distinguish pinworm from malignancy.

Isolated tumor cells in the regional lymph nodes in patients with squamous cell carcinoma of the esophagus are rarely observed but often represent part of a true metastasis.

The most common malignancy of the esophagus is squamous cell carcinoma (SCC) and regional lymph node metastases are an important prognostic factor. Isolated tumor cells (ITCs) are defined as single tumor cells or small clusters of tumor cells not exceeding 0.2 mm. The prognostic role of ITCs is not clear. This study aimed to determine the prevalence of ITCs in regional lymph nodes in patients with esophageal SCC and to investigate how frequently ITCs represent part of a true metastasis. Surgical specimens from 100 patients with SCC of the esophagus were included. All original H&E stained slides containing lymph nodes were reviewed by two gastrointestinal pathologists. In lymph nodes containing ITCs, additional levels were cut and stained with a H&E- and a cytokeratin stain. Areas of tumor cells that measured >0.2 mm on the deeper sections were classified as metastases. A total of 2460 lymph nodes were examined. ITCs were detected in 10 lymph nodes (0.4%) from nine patients (9%). Deeper sections revealed metastases in five out of the 10 lymph nodes (50%). ITCs in regional lymph nodes of patients with SCC of the esophagus is a rare finding compared with patients with adenocarcinoma of the esophagogastric junction. However, deeper sections often revealed metastases. Therefore, in patients with SCC of the esophagus, we recommend additional sectioning and immunohistochemical examination of lymph nodes when ITCs are detected on the first slide.

Isolated tumor cells in regional lymph nodes in patients with adenocarcinoma of the esophagogastric junction might represent part of true metastases.

Regional lymph node metastases in patients with carcinoma of the esophagogastric junction (EGJ) are an important prognostic factor. According to the tumor, node, and metastasis classification, isolated tumor cells (ITCs) are single tumor cells or small clusters of tumor cells not exceeding 0.2 mm. Tumor clusters >0.2 mm are classified as metastases. The significance of lymph nodes with ITCs is unclear, although not contributing to the pN category. The aim of this study was to determine the prevalence of regional lymph nodes with ITCs on the primary hematoxylin and eosin-stained slide and to examine how often deeper sections reveal a true metastasis. The study included surgical specimens of 126 patients with adenocarcinoma of the EGJ. Lymph nodes with ITCs were identified. Additional sections were cut and stained with hematoxylin and eosin and with cytokeratin. All slides were evaluated for the presence of tumor cells, and it was determined whether the criteria for a metastasis were met on the additional sections. ITCs were detected in 59 (1.7%) of 3454 lymph nodes and in 41 (32.5%) of 126 patients. In 29 (49.2%) lymph nodes with ITCs on the primary slide, further sections resulted in a changed status from ITCs to a metastasis. In 7 (17.1%) of 41 patients, the pN category was changed. In patients with adenocarcinoma of the EGJ, the presence of ITCs in regional lymph nodes is a common observation. ITCs often represent part of a real metastasis. To obtain a pN category as accurate as possible, we strongly recommend thorough examination of regional lymph nodes with additional sections when ITCs are observed.