Adenoma-infiltrating lymphocytes (AILs) are a potential marker of hereditary nonpolyposis colorectal cancer

The current value of determining the mismatch repair status of colorectal cancer: A rationale for routine testing

Colorectal Cancer (CRC) is the third most prevalent cancer in men and women. Up to 15% of CRCs display microsatellite instability (MSI). MSI is reflective of a deficient mismatch repair (MMR) system and is most commonly caused by hypermethylation of the MLH1 promoter. However, it may also be due to autosomal dominant constitutional mutations in DNA MMR, termed Lynch Syndrome. MSI may be diagnosed via polymerase chain reaction (PCR) or alternatively, immunohistochemistry (IHC) can identify MMR deficiency (dMMR). Many institutions now advocate universal tumor screening of CRC via either PCR for MSI or IHC for dMMR to guide Lynch Syndrome testing. The association of sporadic MSI with methylation of the MLH1 promoter and an activating BRAF mutation may offer further exclusion criteria for genetic testing. Aside from screening for Lynch syndrome, MMR testing is important because of its prognostic and therapeutic implications. Several studies have shown MSI CRCs exhibit different clinicopathological features and prognosis compared to microsatellite-stable (MSS) CRCs. For example, response to conventional chemotherapy has been reported to be less in MSI tumours. More recently, MSI tumours have been shown to be responsive to immune-checkpoint inhibition providing a novel therapeutic strategy. This provides a rationale for routine testing for MSI or dMMR in CRC.

Biologic and molecular markers for staging colon carcinoma

Biomarkers in the field of pathology and oncology may allow for the detection of disease, assessment of prognosis or to predict response to certain therapy. Molecular abnormalities in colorectal cancer genesis may occur due to chromosome instability, microsatellite instability and DNA methylation (CpG island methylator phenotype). These alterations are associated in some cases to sporadic carcinomas whereas in others are seen in syndrome-related tumors and are the basis for the use of different biomarkers in the clinical setting. These may include mismatched repair gene/proteins, RAS, BRAF, PIK3CA, which help to determine tumor prognosis and predict response to certain drugs.

Mismatch repair deficient-crypts in non-neoplastic colonic mucosa in Lynch syndrome: insights from an illustrative case

Mono-allelic germline mutations in DNA mismatch repair (MMR) genes lead to Lynch syndrome (LS). Questions remain as to the timing of the inactivation of the wild-type allele in LS-associated tumorigenesis. Speculation exists that it happens after the neoplasia has been initiated. However, a recent study reported the presence of MMR-deficiency in non-neoplastic colonic crypts in LS; thus the possibility can be raised that these crypts may be tumor precursors, and as such, biallelic loss of MMR may occur prior to neoplasia. Here we report a unique case that showed findings supporting both of the two seemingly conflicting notions. The patient was a 40-year-old female with LS, MSH2 type, who underwent a segmental colectomy for an adenocarcinoma. By immunohistochemistry, the carcinoma lost MSH2/MSH6. Interestingly, there was also complete loss of MSH2/MSH6 in a distinct focus of 20 colonic crypts that were morphologically non-neoplastic, thus supporting the possibility of biallelic loss of MMR before initiation of neoplasia. However, in a separate adenoma, MMR was preserved in neoplastic glands with low grade dysplasia and lost only in glands with high grade dysplasia, i.e., MMR loss after tumor initiation. These are relevant findings with regard to the timing of MMR deficiency in LS tumorigenesis, and bring forth the possibility that varied tumorigenic pathways may exist. Additionally, we observed that the MMR-deficient non-neoplastic crypts harbored increased intraepithelial CD8-positive T-lymphocytes similar to the patient's carcinoma, providing a potential new venue for the study of the natural antitumor immune responses in LS individuals.

Eosinophils in Colorectal Neoplasms Associated with Expression of CCL11 and CCL24

Background:

A decrease in the number of tissue eosinophils is known to reflect the malignancy potential of neoplastic lesions and even prognosis. Increased levels of the chemokines CCL11 and CCL24 in serum and tissue are also known to have diagnostic value as serum tumor markers or prognostic factors. The aim of this study was to evaluate the correlation between the degree of tissue eosinophilia and the expression of these chemokines in the glandular and stromal cells of colorectal neoplastic lesions ranging from benign to malignant tumors.

Methods:

We counted the number of infiltrating eosinophils in neoplastic lesion tissue and we evaluated the expression of CCL11 and CCL24 in glandular cells and stromal cells by immunohistochemical staining.

Results:

The results showed that the number of eosinophils decreased significantly and the expression of CCL11 and CCL24 in glandular cells decreased with tumor progression, whereas the stromal expression of CCL11 and CCL24 appeared to increase.

Conclusions:

The discrepancy in CCL11 and CCL24 expression between glandular cells and stromal cells might shed light on how colorectal cancer evades the immune system, which would enable further development of immunotherapies that target these chemokines. Further research on eosinophil biology and the expression pattern of chemokines in tumor cells is needed.

Polyposis Syndromes: Role of the Pathologist

This article reviews the major gastrointestinal polyposis syndromes, with an emphasis on the molecular, clinical, and histopathological features of each. Salient features helpful in making or suggesting the diagnosis of these syndromes are discussed, as is the use of ancillary techniques, such as immunohistochemistry and molecular diagnostic studies in diagnosis confirmation and family screening.

Specimens from biopsies of colorectal polyps often harbor additional diagnoses

Objectives. The utility of examining specimens from colorectal biopsies of polyps for nonneoplastic diseases is currently unknown. Our objectives were to characterize such additional diagnoses that could be rendered. Methods. We retrospectively and prospectively reviewed specimens from endoscopic biopsies of colorectal polyps obtained during routine screening or surveillance. Results. 17 of 168 specimens (10.1%) contained additional diagnoses, including schistosomiasis, eosinophilic colitis, intestinal spirochetosis, melanosis coli, and other entities. These findings were easily overlooked because they often affected mucosa that was spared by the polyps or were often evident only at high magnification. Schistosomiasis, eosinophilic colitis, and intestinal spirochetosis were clinically occult. Conclusions. Specimens from biopsies of colorectal polyps often harbor other diagnoses, in addition to polyps, and can be simultaneously screened for polyps and examined for nonneoplastic diseases. Detection of other diagnoses in addition to polyps requires awareness, examination at high magnification, and examination of areas spared by the polyps.

Immunohistochemical testing of conventional adenomas for loss of expression of mismatch repair proteins in Lynch syndrome mutation carriers: a case series from the Australasian site of the colon cancer family registry

Debate continues as to the usefulness of assessing adenomas for loss of mismatch repair protein expression to identify individuals with suspected Lynch syndrome. We tested 109 polyps from 69 proven mutation carriers (35 females and 34 males) belonging to 49 Lynch syndrome families. All polyps were tested by immunohistochemistry for four mismatch repair proteins MLH1, MSH2, MSH6 and PMS2. Detailed pathology review was performed by specialist gastrointestinal pathologists. The majority of polyps (86%) were conventional adenomas (n=94), with 65 tubular and 28 tubulovillous adenomas and a single villous adenoma. The remaining 15 lesions (14%) were serrated polyps. Overall, loss of mismatch repair expression was noted for 78/109 (72%) of polyps. Loss of mismatch repair expression was seen in 74 of 94 (79%) conventional adenomas, and 4 of 15 (27%) serrated polyps from mismatch repair gene mutation carriers. In all instances, loss of expression was consistent with the underlying germline mutation. Mismatch repair protein expression was lost in 27 of 29 adenomas with a villous component compared with 47 of 65 adenomas without this feature (93 vs 73%; P=0.028). A strong trend was observed for high-grade dysplasia. Mismatch repair deficiency was observed in 12 of 12 conventional adenomas with high-grade dysplasia compared with 60 of 79 with low-grade dysplasia (100 vs 76%; P=0.065). We were unable to demonstrate a significant association between conventional adenoma size or site and mismatch repair deficiency. All (4/4 or 100%) of the serrated polyps demonstrating mismatch repair deficiency were traditional serrated adenomas from a single family. Diagnostic testing of adenomas in suspected Lynch syndrome families is a useful alternative in cases where cancers are unavailable. The overwhelming majority of conventional adenomas from mutation carriers show loss of mismatch repair protein expression concordant with the underlying germline mutation.

Comprehensive evaluation of colorectal polyps in specimens from endoscopic biopsies

Modern evaluation of specimens from biopsies of colorectal polyps has become increasingly complex because of tremendous progress in the understanding of colorectal neoplasia. Although pathologists are generally familiar with the basic handling of carcinoma in the setting of polypectomies or resections, the comprehensive evaluation of specimens from biopsies of colorectal polyps obtained with forceps is far from intuitive and has yet to be reviewed. Comprehensive evaluation requires always addressing several key issues, even when dealing with seemingly routine cases. These issues include taking further action when initial sections lack polyps, accurately quantitating polyps, accurately classifying polyps, determining whether thresholds are met for considering conditions at high risk for carcinoma, detecting incidental findings other than polyps, and determining which incidental findings are clinically significant. In particular, polyposis with attenuated phenotype or Lynch syndrome may be clinically occult, and the possibility of these entities should always be kept in mind, regardless of age or history. Ancillary studies performed immediately on carcinoma that is detected at biopsy guides surgery, guides medical therapy, prognosticates, provides evidence for hereditary neoplasia, and guides surveillant colonoscopy for the family.

Current hypotheses on how microsatellite instability leads to enhanced survival of Lynch Syndrome patients

High levels of microsatellite instability (MSI-high) are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS) colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI-high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.

In Lynch syndrome adenomas, loss of mismatch repair proteins is related to an enhanced lymphocytic response

AIMS

Lynch syndrome-associated tumours are characterized by the presence of an increased number of tumour-infiltrating lymphocytes. This enhanced lymphocytic response may be elicited by genetically altered proteins that may arise as a result of a defective DNA mismatch repair system. The aim was to investigate this hypothesis by correlating loss of mismatch repair proteins and infiltration of lymphocytes in Lynch syndrome-associated adenomas and hyperplastic polyps.

METHODS AND RESULTS

Mismatch repair protein expression and the number of tumour-infiltrating lymphocytes were assessed in Lynch syndrome (41 adenomas and nine hyperplastic polyps) and in familial colorectal cancer (nine adenomas and one hyperplastic polyp). Nineteen sporadic adenomas were included as a control group. Twenty of 32 (63%) adenomas with loss of mismatch repair protein expression showed an increase in tumour-infiltrating lymphocytes. Eight adenomas (8/32; 25%) displayed many tumour-infiltrating lymphocytes, whereas most adenomas (12/32; 38%) showed a minor increase. In adenomas with mismatch repair protein expression, both sporadic and Lynch syndrome associated, not one showed an increased number of tumour-infiltrating lymphocytes. Hyperplastic polyps in Lynch syndrome patients showed neither loss of mismatch repair expression nor an increase in tumour-infiltrating lymphocytes.

CONCLUSIONS

There is a correlation between the loss of mismatch repair proteins and the infiltration of lymphocytes in Lynch syndrome-associated adenomas.

Patient with eight metachronous gastrointestinal cancers thought to be hereditary nonpolyposis colorectal cancer (HNPCC)

An 81-year-old woman presented with a chief complaint of swelling of both lower legs. She had a history of surgery for cancers of the stomach, rectum and colon. Among her immediate family members, her son had colon and rectal cancers, and her sister had ovarian cancer. After close examination the patient was diagnosed with small intestine cancer and ascending colon cancer. Gene mutation analyses did not reveal any mutations in DNA mismatch repair genes, but MSH-2 protein expression was lost only in the cancer lesions. Here, we report this rare case of eight metachronous gastrointestinal cancers thought to be HNPCC.

Tumor infiltrating lymphocytes but not serum pituitary antibodies are associated with poor clinical outcome after surgery in patients with pituitary adenoma

CONTEXT

Serum pituitary antibodies (Pit Abs) and tumor-infiltrating lymphocytes (TILs) have been described in pituitary adenomas, but their clinical significance remains unknown.

OBJECTIVE

The objective of the study was to assess Pit Abs and TILs prevalence in pituitary adenomas and their influence on clinical outcome.

DESIGN

This was a prevalence case-control study.

PATIENTS AND SETTING

Two hundred ninety-one pituitary adenoma cases (110 non-secreting, 30 ACTH-69 GH-71 prolactin- and 13 TSH-secreting adenoma; 177 operated and 114 untreated), 409 healthy controls, and 14 autoimmune hypophysitis were enrolled in a tertiary referral center.

INTERVENTION

Pit Abs were measured using immunofluorescence in all cases and controls (n = 714). The presence of TILs was evaluated using CD45 staining in a subset of adenomas surgically treated (n = 72).

MAIN OUTCOME MEASURE

Clinical response of pituitary adenoma after surgery was evaluated.

RESULTS

Pit Abs prevalence was higher in adenomas (5.1%) than healthy subjects (0.7%, P < 0.0001) and lower than in autoimmune hypophysitis patients (57%, P < 0.0001). Similarly, TILs prevalence was higher in adenomas than normal pituitary (P = 0.01) and lower than in autoimmune hypophysitis (P < 0.0001). No correlation between Pit Abs and TILs was found (P = 0.78). A poor clinical outcome was more common in adenoma patients with TILs (11 of 18, 61%) than in those without (17 of 54, 31%, P = 0.026). Multivariate regression analysis identified the presence of TILs as independent prognostic factor for persistence/recurrence of pituitary adenoma.

CONCLUSIONS

TILs and Pit Abs are present in a significant number of pituitary adenoma patients. Cell-mediated immunity appears to be predictive of a less favorable clinical outcome.