Annexin A10 is a marker for the serrated pathway of colorectal carcinoma.

Serrated adenocarcinoma (SAC), representing at least 10 % of colorectal carcinomas (CRC), differs from conventional carcinomas not only by its histology, but also by its molecular basis. However, the diagnosis of SAC in poorly differentiated cases and without an adjacent serrated adenoma can be challenging. In this study, we utilized previously described expression data and identified annexin A10 (ANXA10) as a potential marker for SAC. We conducted ANXA10 immunohistochemistry in groups of 146 CRC patients and 131 serrated and conventional polyps. In CRC cases, ANXA10 expression associated with serrated histology (sensitivity 42 % and specificity 98 %). BRAF V600E mutation correlated with ANXA10 expression but also seven BRAF wild-type tumors (5 %) were positive for ANXA10. Immunoreactivity for either ANXA10 or BRAF V600E was an accurate predictor of serrated histology (sensitivity 55 % and specificity 97 %). ANXA10 expression did not associate with tumor stage or grade. Of the 131 colorectal polyps, 30/30 of sessile serrated adenomas, 6/11 traditional serrated adenomas, 20/32 hyperplastic polyps, and 2/27 tubulovillous adenomas were positive for ANXA10, while 31/31 tubular adenomas were negative. In conclusion, the results suggest that ANXA10 is a marker with high specificity for the serrated pathway of CRC.

VE1 immunohistochemistry accurately detects BRAF V600E mutations in colorectal carcinoma and can be utilized in the detection of poorly differentiated colorectal serrated adenocarcinoma.

Serrated adenocarcinoma (SAC) is a recently defined subtype of colorectal carcinoma (CRC). However, in cases where an adjacent serrated adenoma is absent and the differentiation is poor, the diagnosis of SAC can be challenging. BRAF V600E mutation is a characteristic molecular change for the serrated route, but the utility of the newly described BRAF V600E-specific immunohistochemistry in the recognition of SAC is unclear. In this study, we conducted immunohistochemical determination of BRAF V600E mutation and correlated the results to BRAF mutation status and the histological features of SAC in a cohort of 147 CRC patients. There were 13 (8.8 %) BRAF-mutated CRCs confirmed by DNA sequencing. The sensitivity of immunohistochemistry in detecting BRAF V600E mutation was 100 % (13/13) and the specificity was 99.3 % (133/134). Three evaluators independently analyzed the immunohistochemical sections and the correlation between all the evaluators was perfect (κ = 1). In histologic examination, 33 (22.4 %) of the CRCs were classified as SACs. Twelve of 13 (92.3 %) BRAF-mutated CRCs were evaluated to represent serrated type growth pattern. One of 13 (7.7 %) showed poor differentiation not enabling convincing classification. In conclusion, we found immunohistochemistry to be accurate in the detection of the BRAF V600E mutation, with potential applications in the recognition of the BRAF-mutated SACs. Especially in cases where the adjacent adenoma is absent and the tumor is poorly differentiated, BRAF immunohistochemistry could be utilized as an aid to detect SACs.

Characteristics and significance of colorectal cancer associated lymphoid reaction.

A subset of colorectal cancers (CRCs) exhibits so-called Crohn's like lymphoid reaction (CLR), an inflammatory reaction pattern that consists of numerous transmural lymphoid aggregates. However, the composition of these aggregates, their biological mechanisms and their prognostic significance are not well-defined. We analyzed two CRC cohorts (418 and 149 patients) and determined clinicopathological features including survival. A new method for evaluating CLR based on counting the areal density of the lymphoid follicles (CLR density) was adopted. Immune cell densities at intratumoral and peritumoral regions, as well as the composition of the lymphoid follicles, were studied by immunohistochemistry. We found that CLR comprised of lymphoid aggregates with no evidence of granuloma formation. High CLR density associated with lower tumor stage, lack of preoperative radiotherapy or chemoradiotherapy and deficient mismatch repair enzyme expression. CLR density had positive correlations with peritumoral and intratumoral densities of CD83(+) mature dendritic cells and T cells. High CLR density associated with better survival and had prognostic value that was independent of stage, Klintrup-Mäkinen score for peritumoral inflammation and the numbers of tumor infiltrating T cells. CLR density evaluation had excellent intraobserver and interobserver agreement. In conclusion, the results suggest that CLR contributes to the adaptive antitumor immunity. Quantitative evaluation of CLR density is a relevant prognostic indicator in CRC.

An improved image analysis method for cell counting lends credibility to the prognostic significance of T cells in colorectal cancer.

Numerous immunohistochemically detectable proteins, such as immune cell surface (CD) proteins, vascular endothelial growth factor, and matrix metalloproteinases, have been proposed as potential prognostic markers in colorectal cancer (CRC) and other malignancies. However, the lack of reproducibility has been a major problem in validating the clinical use of such markers, and this has been attributed to insufficiently robust methods used in immunohistochemical staining or its assessment. In this study, we assessed how computer-assisted image analysis might contribute to the reliable assessment of positive area percentage and immune cell density in CRC specimens, and subsequently, we applied the computer-assisted cell counting method in assessing the prognostic value of T cell infiltration in CRC. The computer-assisted analysis methods were based on separating hematoxylin and diaminobenzidine color layers and then applying a brightness threshold using open source image analysis software ImageJ. We found that computer-based analysis results in a more reproducible assessment of the immune positive area percentage than visual semiquantitative estimation. Computer-assisted immune cell counting was rapid to perform and accurate (Pearson r > 0.96 with exact manual cell counts). Moreover, the computer-assisted determination of peritumoral and stromal T cell density had independent prognostic value. Our results suggest that computer-assisted image analysis, utilizing freely available image analysis software, provides a valuable alternative to semiquantitative assessment of immunohistochemical results in cancer research, as well as in clinical practice. The advantages of using computer-assisted analysis include objectivity, accuracy, reproducibility, and time efficiency. This study supports the prognostic value of assessing T cell infiltration in CRC.