DNA Mismatch Repair Protein Deficiency Research Articles

The prevalence of lynch syndrome (DNA mismatch repair protein deficiency) in patients with primary localized prostate cancer using immunohistochemistry screening

BackgroundProstate cancer is one of the most heritable human cancers. Lynch syndrome is an autosomal dominant inheritance caused by germline mutations in DNA mismatch repair (MMR) genes, which are also associated with an increased incidence of prostate cancer. However, prostate cancer has not been defined as a Lynch syndrome-associated cancer. The proportion of Lynch syndrome patients in primary prostate cancers is unclear. In this study, we investigated MMR protein loss using universal immunohistochemical screening to determine the prevalence of Lynch syndrome in patients with localized prostate cancer who underwent radical prostatectomy.MethodsOne hundred twenty-nine surgical specimens from radical prostatectomy performed at Toranomon Hospital between 2012 and 2015 were retrospectively tested using universal screening with immunohistochemistry staining for expression of the MMR proteins MLH1, PMS2, MSH2, and MSH6. For all suspected MMR-deficient patients, germline genetic tests focusing on MMR genes were performed.ResultsMMR protein loss was found in only one patient (0.8%) who showed dual MSH2/MSH6 loss. This patient showed a single nucleotide pathogenic germline mutation from c.1129 C to T (p.Gln377*) at exon 7 in the MSH2 gene. He was diagnosed with a primary prostate cancer at 66 years of age. He had a documented history of Lynch syndrome (Muir–Torre syndrome) with previous colon cancer, sebaceous tumor, and keratoacanthoma as well as subsequent bladder cancer, all of which also showed dual MSH2/MSH6 loss. He also had a strong family history of colorectal and other Lynch syndrome-associated cancers. The pathological stage was pT3aN0M0, and the pathological grade was Gleason 7(4 + 3) with tertiary pattern 5.ConclusionsIn this study, immunohistochemical screening of MMR proteins for Lynch syndrome was performed in a series of prostate cancer cases. The prevalence of Lynch syndrome in localized prostate cancer was 0.8%, which is low compared with other Lynch syndrome-associated cancers.

Loss of SATB2 and CDX2 expression is associated with DNA mismatch repair protein deficiency and BRAF mutation in colorectal cancer.

The relationship between the expression of the SATB2 and CDX2 proteins and common molecular changes and clinical prognosis in colorectal cancer (CRC) still needs further clarification. We collected 1180 cases of CRC and explored the association between the expression of SATB2 and CDX2 and clinicopathological characteristics, molecular alterations, and overall survival of CRC using whole-slide immunohistochemistry. Our results showed that negative expression of SATB2 and CDX2 was more common in MMR-protein-deficient CRC than in MMR-protein-proficient CRC (15.8% vs. 6.0%, P = 0.001; 14.5% vs. 4.0%, P = 0.000, respectively). Negative expression of SATB2 and CDX2 was more common in BRAF-mutant CRC than in BRAF wild-type CRC (17.2% vs. 6.1%, P = 0.003; 13.8% vs. 4. 2%; P = 0.004, respectively). There was no relationship between SATB2 and/or CDX2 negative expression and KRAS, NRAS, and PIK3CA mutations. The lack of expression of SATB2 and CDX2 was associated with poor histopathological features of CRC. In multivariate analysis, negative expression of SATB2 (P = 0.030), negative expression of CDX2 (P = 0.043) and late clinical stage (P = 0.000) were associated with decreased overall survival of CRC. In conclusion, the lack of SATB2 and CDX2 expression in CRC was associated with MMR protein deficiency and BRAF mutation, but not with KRAS, NRAS and PIK3CA mutation. SATB2 and CDX2 are prognostic biomarkers in patients with CRC.

Clinicopathological characteristics of endometrial carcinomas according to DNA mismatch repair protein status

DNA mismatch repair protein deficiency (MMRd) in endometrial carcinoma is associated with the risk of Lynch syndrome and response to immune checkpoint inhibitors. It is also related to microsatellite instability and corresponds to a molecular subtype of endometrial tumor with an unclear prognosis. Here, we evaluated the clinicopathological characteristics and prognosis of 312 consecutive endometrial carcinoma cases submitted to complete surgical staging at a single institution. We compared MMRd and mismatch repair protein–proficient (MMRp) tumors and examined the effects of the MMR protein loss type (MLH1/PMS2 vs. MSH2/MSH6) and influence of L1CAM and p53 expression. The median follow-up period was 54.5 (range, 0–120.5) months. No difference was observed between MMRd [n = 166 (37.2%)] and MMRp [n = 196 (62.8%)] cases in terms of age, body mass index, FIGO stage, tumor grade, tumor size, depth of myometrial infiltration, or lymph node metastasis. More MMRd than MMRp tumors had endometrioid histology (87.9% vs. 75.5%) and despite MMRd had more lymphovascular space invasion (LVSI; 27.2% vs. 16.9%), they presented fewer recurrences and no difference in lymph node metastasis and disease-related death. Relative to those with MLH1/MSH6 loss, tumors with MSH2/MSH6 loss were diagnosed at earlier FIGO stages, were smaller, and had less ≥50% myometrial invasion, LVSI and lymph node metastasis. Outcomes, however, did not differ between these groups. L1CAM positivity and mutation-type p53 expression were more common in MMRp than in MMRd tumors and did not differ between the MLH1/PMS2 and MSH2/MSH6 loss groups. In the entire cohort, L1CAM and mutation p53 expression were associated with worse prognosis, but only non-endometrioid histology, FIGO stage III/IV, and deep myometrial infiltration were significant predictors. In the subgroup of endometrioid carcinomas, only FIGO stage III/IV was associated with poor outcomes. The risk of lymph node metastasis was associated with tumor size, non-endometrioid histology, and multifocal LVSI. For MMRd tumors, only tumor size and myometrial invasion depth were predictive of lymph node involvement. In our cohort, MMRd tumors were associated with greater recurrence-free, but not overall, survival. The precise identification of MMRd status, present in a substantial proportion of endometrial cancer cases, is a challenge to be overcome for proper patient management. MMRd status serves as a marker for Lynch syndrome, and a significant number of these tumors are high risk and candidate to immunotherapy.

Nectin-4 as a Predictive Marker for Poor Prognosis of Endometrial Cancer with Mismatch Repair Impairment.

The adhesion molecule Nectin-4 is a new potential therapeutic target for different types of cancer; however, little is known about its diagnosis significance in endometrial cancer (EC). We found that Nectin-4 expression was significantly higher in EC tissues than in nonadjacent normal tissue. The area under the receiver operating characteristic curve value of 0.922 indicated good diagnostic accuracy for Nectin-4 expression in EC. Furthermore, Nectin-4 expression was associated with DNA mismatch repair (MMR) protein deficiency. Notably, the high Nectin-4 expression group of patients with MSH2/6-deficient EC had shorter progression-free survival than that of the low Nectin-4 expression group. The number of lymphovascular space invasion-positive patients in groups with MMR deficiency and high Nectin-4 expression was also increased compared with that in the low Nectin-4 expression group. Bioinformatics analysis revealed that alteration in Nectin-4 and MMR genes is associated with Nectin-4 expression in EC. To the best of our knowledge, this is the first study to show that Nectin-4 expression may be a potential biomarker for EC diagnosis and that high Nectin-4 expression in MMR-deficient patients with EC can predict short progression-free survival, thus providing clues to identify patients for adjuvant therapy.

Development of novel models for predicting mismatch repair protein deficiency and relevant disease-free survival in colorectal cancer patients.

DNA mismatch repair (MMR) protein deficiency has attached more attention for its potential to be a biomarker of immunotherapy for colorectal cancer (CRC) patients. However, clinical models involving the expression status of MMR protein are rare. Herein, we sought to develop two clinical models (a diagnostic model for the prediction of MMR status and a prognostic model for the prediction of disease-free survival) for CRC patients. A total of 582 CRC patients were finally included. There were 53 patients with deficient expression of MMR protein. The differences between the deficient MMR (dMMR) group and the proficient MMR (pMMR) group were analyzed. Compared to pMMR patients, those with dMMR status were younger and had better pathological features (depth of invasion, lymph node metastasis, distant metastasis, pathological stage, perineuronal invasion, and PLT level) and disease-free survival (DFS). The tumor location of the left colon, adenocarcinoma, and abnormal PLT level were identified as the independent predictors for pMMR. Based on these data, we developed the diagnostic model using Logistic regression analysis. It showed a satisfactory accuracy (AUC = 82.3% in the derivate set; AUC = 73.6% in the validation set). Furthermore, pMMR, poorer differentiation, perineuronal invasion, distant metastasis, lower hemoglobin level, and abnormal CEA level were established as the independent prognostic factors of poorer DFS. Based on them, a prognostic model with valuable performance (1-year AUC = 75.5%/3-year AUC = 76.9% in the derivate set; 1-year AUC = 72.3%/3-year AUC = 73.8% in the validation set) was developed. Our diagnostic and prognostic models could identify CRC patients at risk for pMMR protein expression and disease recurrence. It may contribute to improving the diagnosis and treatment of CRC patients at an individual level.

DNA mismatch repair-deficient non-neoplastic endometrial glands are common in Lynch syndrome patients and are present at a higher density than in the colon.

The hallmark of Lynch syndrome (LS) is DNA mismatch repair protein (MMR) deficiency. Recently, MMR deficiency in non-neoplastic colonic crypts has been identified as a novel indicator of LS. We aimed to determine whether MMR-deficient non-neoplastic endometrial glands can distinguish patients with and without LS, and to compare the level of MMR deficiency in the normal endometrium and colon in LS patients. We evaluated the immunohistochemical expression of MMR proteins in the normal endometrial mucosa from 64 patients, including 34 patients with confirmed LS (17 with endometrial cancer and 17 without cancer), 30 patients with endometrial cancer without LS (10 with tumours with MLH1 promoter hypermethylation and 20 with MMR-proficient tumours), and in the normal colonic mucosa from 30 LS patients. MMR-deficient non-neoplastic endometrial glands were identified in 47% of LS patients and in no patients without LS (P<0.001). MMR-deficient non-neoplastic glands were more often identified in LS patients with endometrial cancer (65%) than in those without endometrial cancer (29%) (P=0.04). In contrast to what was seen in the normal colon, MMR-deficient glands in the normal endometrium were seen as large, contiguous groups, ranging in number from two to 101 (87% versus 45%, P=0.02). MMR-deficient glands were identified at a higher density in the endometrium than in the colon in LS patients (median number of MMR-deficient glands, 22 versus two, P=0.02). Our findings indicate that MMR-deficient non-neoplastic endometrial glands constitute an indicator of LS, and that MMR-deficient glands in the endometrium are present in a pattern of contiguous large groups.

DNA mismatch repair deficiency and p53 abnormality are age-related events in mixed endometrial carcinoma with a clear cell component

Mixed endometrial carcinoma (MEC) is defined as a tumor composed of two or more spatially distinct subtypes, at least one of which is serous or clear cell carcinoma. In this study, the clinicopathological features of 15 MEC cases containing a clear cell component (MEC-C) were investigated. The ages of patients ranged from 32 to 83 years (median, 61 years). The combinations of carcinoma components observed were endometrioid and clear cell in ten patients; endometrioid, clear cell and serous in three; and clear cell and serous in two. Immunohistochemically, nine had DNA mismatch repair (MMR) protein deficiency (MMR-d), nine had loss of ARID1A and three cases had aberrant p53 expression. MMR-d and loss of ARID1A showed a strong correlation. Only one case showed both MMR-d and aberrant p53 expression. The patients with MMR-d were younger than those without MMR-d (median; 58 years vs. 71 years). Loss of ARID1A also showed significant predilection for younger women than ARID1A intact cases. In conclusion, MMR-d was observed in 60 % of MEC-C, showed predilection for young women, and was associated with ARID1A loss. In contrast, non- MMR-d MEC-C occurred in elder women and some tumors may associate with TP53 mutation. These findings suggest that MEC-C develop via two different molecular mechanisms and they are age-related events.

Clinicopathological, molecular features and prognosis of colorectal cancer with mucinous component.

Background: Colorectal cancer (CRC) with mucinous component is associated with distinct characteristics and controversial prognosis. Patients & methods: A total of 1800 CRC patients were retrospectively enrolled and grouped by the mucinous content of the primary tumors. The clinicopathological characteristics and overall survival rate were compared between groups. Results: Mucinous adenocarcinoma (MAC) and adenocarcinoma with mucinous component (AMC) had higher frequencies of DNA mismatch repair protein deficiency, KRAS, BRAF and PIK3CA mutations as compared to those of conventional adenocarcinoma (CAC). MAC had worse prognosis than CAC. However, MAC was not an independent prognostic factor in multivariable analysis. Conclusion: Molecular features of AMC and MAC were similar, which were different from those of CAC. Neither MAC nor AMC were independent prognostic factors for CRC.

Frequency and clinicopathologic associations of DNA mismatch repair protein deficiency in ampullary carcinoma: Routine testing is indicated.

The significance of DNA mismatch repair (MMR) deficiency in ampullary cancers (ACs) has not been established. In total, 127 ACs with invasive carcinomas measuring ≥3 mmthat had adequate tissue were analyzed immunohistochemically. MMR loss was detected in 18% of ACs (higher than in colorectal cancers). Twelve tumors with MLH1-PMS2 loss were negative for BRAF V600E mutation, suggesting a Lynch syndrome association. MMR-deficient tumors (n=23), comparedwith MMR-intact tumors (n=104), showed a striking male predominance (male:female ratio, 4.7). Although the deficient tumors had slightly larger invasion size (2.7 vs 2.1 cm), they also had more expansile growth and less invasiveness, including less perineural invasion, and they ultimately had lower tumor (T) classification and less lymph node metastasis (30% vs 53%; P=.04). More important, patients who had MMR-deficient tumors had better clinical outcomes, with a 5-year overall survival rate of 68% versus 45% (P=.03), which was even more pronounced in those who had higher Tclassification (5-year overall survival, 69% vs 34%; P=.04). MMR deficiencyhad a statistically significant association with medullary phenotype, pushing-border invasion, and tumor-infiltrating immune cells, and it occurred more frequently in ampullary-duodenal type tumors. Programed cell death-ligand 1 (PD-L1) levels analyzed in the 22 MMR-deficient ACs revealed that all medullary carcinomas were positive. Nonmedullary MMR-deficient carcinomas expressed PD-L1 in 33% of tumors cells according to the criteria for a combined positive score ≥1, but all were negative according to the tumor proportion score≥1 method. In ACs, MMR deficiency is even more frequent (18%) than in colon cancer and often has a Lynch-suggestive profile, thus routine testing is warranted. Male gender, pushing-border infiltration, ampullary-duodenal origin, medullary histology, and tumor-related inflammation have a significantly higher association with MMR deficiency. MMR-deficient tumors have less aggressive behavior. PD-L1 expression is common in medullary-phenotype ACs, thus immunotherapy should be considered at least for this group.

Targeted next generation sequencing of MLH1-deficient, MLH1 promoter hypermethylated, and BRAF/RAS-wild-type colorectal adenocarcinomas is effective in detecting tumors with actionable oncogenic gene fusions.

Oncogenic gene fusions represent attractive targets for therapy of cancer. However, the frequency of actionable genomic rearrangements in colorectal cancer (CRC) is very low, and universal screening for these alterations seems to be impractical and costly. To address this problem, several large scale studies retrospectivelly showed that CRC with gene fusions are highly enriched in groups of tumors defined by MLH1 DNA mismatch repair protein deficiency (MLH1d), and hypermethylation of MLH1 promoter (MLH1ph), and/or the presence of microsatellite instability, and BRAF/KRAS wild-type status (BRAFwt/KRASwt). In this study, we used targeted next generation sequencing (NGS) to explore the occurence of potentially therapeutically targetable gene fusions in an unselected series of BRAFwt/KRASwt CRC cases that displayed MLH1d/MLH1ph. From the initially identified group of 173 MLH1d CRC cases, 141 cases (81.5%) displayed MLH1ph. BRAFwt/RASwt genotype was confirmed in 23 of 141 (~16%) of MLH1d/MLH1ph cases. Targeted NGS of these 23 cases identified oncogenic gene fusions in nine patients (39.1%; CI95: 20.5%-61.2%). Detected fusions involved NTRK (four cases), ALK (two cases), and BRAF genes (three cases). As a secondary outcome of NGS testing, we identified PIK3K-AKT-mTOR pathway alterations in two CRC cases, which displayed PIK3CA mutation. Altogether, 11 of 23 (~48%) MLH1d/MLH1ph/BRAFwt/RASwt tumors showed genetic alterations that could induce resistance to anti-EGFR therapy. Our study confirms that targeted NGS of MLH1d/MLH1ph and BRAFwt/RASwt CRCs could be a cost-effective strategy in detecting patients with potentially druggable oncogenic kinase fusions.

Automated Quantitation of CD8-positive T Cells Predicts Prognosis in Colonic Adenocarcinoma With Mucinous, Signet Ring Cell, or Medullary Differentiation Independent of Mismatch Repair Protein Status

Despite their association with DNA mismatch repair (MMR) protein deficiency, colonic adenocarcinomas with mucinous, signet ring cell, or medullary differentiation have not been associated with improved survival compared with conventional adenocarcinomas in most studies. Recent studies indicate that increased T-cell infiltration in the tumor microenvironment has a favorable prognostic effect in colonic adenocarcinoma. However, the prognostic effect of tumor-associated T cells has not been evaluated in histologic subtypes of colonic adenocarcinoma. We evaluated CD8-positive T-cell density in 259 patients with colonic adenocarcinoma, including 113 patients with tumors demonstrating mucinous, signet ring cell, or medullary differentiation, using a validated automated quantitative digital image analysis platform and correlated CD8-positive T-cell density with histopathologic variables, MMR status, molecular alterations, and survival. CD8-positive T-cell densities were significantly higher for MMR protein-deficient tumors (P<0.001), BRAF V600E mutant tumors (P=0.004), and tumors with medullary differentiation (P<0.001) but did not correlate with mucinous or signet ring cell histology (P>0.05 for both). In the multivariable model of factors predicting disease-free survival, increased CD8-positive T-cell density was associated with improved survival both in the entire cohort (hazard ratio=0.34, 95% confidence interval, 0.15-0.75, P=0.008) and in an analysis of patients with tumors with mucinous, signet ring cell, or medullary differentiation (hazard ratio=0.06, 95% confidence interval, 0.01-0.54, P=0.01). The prognostic effect of CD8-positive T-cell density was independent of tumor stage, MMR status, KRAS mutation, and BRAF mutation. Venous invasion was the only other variable independently associated with survival in both the entire cohort and in patients with tumors with mucinous, signet ring cell, or medullary differentiation. In summary, our results indicate that the prognostic value of MMR protein deficiency is most likely attributed to increased tumor-associated CD8-positive T cells and that automated quantitative CD8 T-cell analysis is a better biomarker of patient survival, particularly in patients with tumors demonstrating mucinous, signet ring cell, or medullary differentiation.

Detection of DNA mismatch repair deficient crypts in random colonoscopic biopsies identifies Lynch syndrome patients.

The hallmark of Lynch syndrome (LS)-associated neoplasia is DNA mismatch repair protein (MMR) deficiency. Recent studies have demonstrated that histologically normal colonic crypts in patients with LS can exhibit deficient MMR expression. The aim of this study was to determine the feasibility of detecting MMR deficient crypts in random colonoscopic biopsies of normal mucosa in patients with and without LS. Forty-nine patients, including 33 with LS, 12 without LS, and 4 with germline MMR gene variants of uncertain significance (VUS), were prospectively and blindly evaluated by immunohistochemistry for MMR deficient crypts within random normal-appearing mucosal biopsies obtained during surveillance colonoscopy. MMR deficient crypts were identified in 70% (23/33) of patients with LS and in no patients without LS (0/12) (p < 0.001). MMR deficient crypts were identified with nearly equal frequency in both LS patients with and without a cancer history and were associated with germline variants in all four MMR genes and EPCAM. MMR deficient crypts were also identified in LS patients with a history of non-colorectal cancer types, including patients with endometrial cancer, skin sebaceous neoplasms, and renal cancer. Two of the four patients with germline MMR gene VUS had MMR deficient crypts. In conclusion, MMR deficient crypts are a specific biomarker of LS and can be identified in random normal mucosal biopsies in LS patients. Evaluation for MMR deficient crypts in colonoscopic biopsies of normal mucosa can help identify LS patients.

Loss of ARID1A expression is associated with DNA mismatch repair protein deficiency and favorable prognosis in advanced stage surgically resected esophageal adenocarcinoma

Esophageal adenocarcinoma often presents at an advanced stage and has a dismal prognosis. Current prognostic markers have limited utility. ARID1A is implicated as a tumor suppressor gene in esophageal adenocarcinoma. Loss of ARID1A expression correlates with DNA mismatch repair (MMR) protein deficiency in other tumors. We hypothesized that ARID1A loss is associated with prognosis and DNA MMR protein deficiency in esophageal adenocarcinoma. Tissue microarrays representing 316 surgically resected esophageal adenocarcinomas without neoadjuvant treatment were evaluated for ARID1A and MMR proteins by immunohistochemistry. Loss of ARID1A expression (ARID1A-loss) was detected in 41 of 316 (13%) adenocarcinomas. MMR deficiency was identified in 5% (17/316) but was detected more frequently in ARID1A-loss adenocarcinomas (13/41, 32%) than in ARID1A-retained adenocarcinomas (4/275, 1%; P < .001). Morphologically, ARID1A-loss adenocarcinomas frequently demonstrated peritumoral lymphoid aggregates (90%) and tumor infiltrating lymphocytes (51%). In patients with locally advanced or metastatic disease (stages III or IV, N = 169), patients with ARID1A-loss adenocarcinomas (N = 22) had longer overall survival than patients with ARID1A-retained adenocarcinomas (median [month]: 26 vs. 16, P = .010). In these patients, ARID1A-loss correlated with a 56% reduction in mortality independent of other prognostic factors (P = .007). In summary, loss of ARID1A expression is associated with DNA MMR protein deficiency in esophageal adenocarcinoma. Furthermore, ARID1A loss is independently associated with a more favorable prognosis for patients with locally advanced or metastatic esophageal adenocarcinomas.

Evaluation of DNA Mismatch Repair Protein Deficiency in Primary Endometrial Carcinoma

Abstract Objective: Many familial and sporadic endometrial carcinomas have microsatellite instability (MSI) due to mutations in the DNA mismatch repair (MMR) genes. Immunohistochemistry (IHC) for M...

DNA mismatch repair deficiency but not ARID1A loss is associated with prognosis in small intestinal adenocarcinoma

Small intestinal adenocarcinoma is an uncommon neoplasm with poor prognosis. It is clinically approached similarly to colorectal carcinoma (CRC). The prognostic value of DNA mismatch repair protein deficiency (dMMR) in CRC is well established, but its role in small intestinal adenocarcinoma remains inconclusive. Recently, loss of expression of ARID1A, a tumor suppressor gene product, by immunohistochemistry (IHC) was linked to dMMR and poor outcome in small intestinal adenocarcinoma, suggesting that it may be an emerging prognostic biomarker. We hypothesized that dMMR and/or ARID1A loss may be associated with clinical outcome in small intestinal adenocarcinoma. We examined dMMR and ARID1A loss by IHC in 120 surgically resected, nonampullary small intestinal adenocarcinomas collected from 2 tertiary centers. ARID1A loss was detected in 6 (7%) of 92 ARID1A-stained adenocarcinomas, whereas 21 (18%) of 120 adenocarcinomas demonstrated dMMR. ARID1A loss was not associated with survival or dMMR. dMMR adenocarcinomas had no distant metastasis, whereas 22 (22%) of 99 MMR-proficient adenocarcinomas had (P = .01). dMMR was an independent, positive predictor of disease-free survival (P = .035, hazard ratio: 0.2). Compared with dMMR CRC, dMMR small intestinal adenocarcinomas more frequently demonstrated loss of MSH2 and MSH6 and less often showed loss of MLH1 and PMS2 (both P < .001). In summary, ARID1A loss by IHC is uncommon in small intestinal adenocarcinomas. dMMR small intestinal adenocarcinomas are nonmetastatic tumors, frequently demonstrate loss of MSH2 and MSH6, and have superior disease-free survival. Our results suggest that all small intestinal adenocarcinomas should be tested for MMR protein deficiency.

Loss of SATB2 Expression in Colorectal Carcinoma Is Associated With DNA Mismatch Repair Protein Deficiency and BRAF Mutation.

The special AT-rich sequence binding protein (SATB2) has been reported to be a specific immunohistochemical marker for colorectal carcinoma; however, correlation of SATB2 expression with molecular alterations commonly assessed in colorectal carcinoma has not been performed. We examined the immunohistochemical expression of SATB2 in 586 adenocarcinomas of the gastrointestinal (GI) tract and pancreas to assess its utility in diagnosis and analyze the clinicopathologic and molecular characteristics of colorectal carcinoma stratified by SATB2 expression. SATB2 and CDX2 expression were evaluated in 266 adenocarcinomas of lower GI tract origin (246 colorectal and 20 appendiceal mucinous), 208 adenocarcinomas of upper GI tract and small intestinal origin (74 esophagus/esophagogastric junction, 103 stomach, 20 duodenal, and 11 jejunoileal), and 112 pancreatic ductal adenocarcinomas. SATB2 expression was more frequently identified in adenocarcinomas of lower GI tract origin (222/266, 83%) compared with upper GI tract, small intestinal, or pancreatic origin (26/320, 8%) (P<0.001). Compared with CDX2 alone, dual positive expression for SATB2 and CDX2 (SATB2/CDX2) has a significantly higher specificity for adenocarcinoma of lower GI tract origin (94% vs. 57%, P<0.001). In colorectal carcinoma, loss of SATB2 expression was more frequently observed in DNA mismatch repair (MMR) protein deficient tumors (31%) compared with MMR protein proficient tumors (13%) (P<0.01). A BRAF V600E mutation was more frequently identified in colorectal carcinomas with loss of SATB2 expression compared with those with positive SATB2 expression (29% vs. 3%) (P<0.001). In summary, SATB2 expression is a relatively specific marker of lower GI tract origin; however, loss of SATB2 expression is more commonly seen in colorectal carcinoma with MMR protein deficiency and BRAF mutation.

Sebaceous Neoplasms With Rippled, Labyrinthine/Sinusoidal, Petaloid, and Carcinoid-Like Patterns: A Study of 57 Cases Validating Their Occurrence as a Morphological Spectrum and Showing No Significant Association With Muir-Torre Syndrome or DNA Mismatch Repair Protein Deficiency.

Sebaceous neoplasms with an organoid pattern (rippled, labyrinthine/sinusoidal, carcinoid-like, and petaloid) are rare. Previous studies suggested that the above patterns likely represent variations along a morphological continuum. The objectives of this study were to (1) validate this proposition by studying a large number of cases, (2) determine whether there are specific associations with clinical features, (3) establish their frequency, and (4) determine whether they have any association with Muir-Torre syndrome. Fifty-seven sebaceous neoplasms (54 sebaceomas and 3 sebaceous carcinomas) with organoid growth patterns were studied. These occurred in 36 men and 18 women (sex unknown in 3), with ages at diagnosis ranging from 22 to 89 years (mean, 63 years). All patients presented with a solitary nodule (mean size, 11 mm) on the head and neck area. Of the 57 tumors, 24 manifested a single growth pattern, 23 had a combination of 2 patterns, and 10 a combination of 3 patterns, indicating that these patterns are part of a morphological continuum of changes. The carcinoid-like pattern was the most frequent in the "monopatterned" neoplasms (13 cases), whereas the labyrinthine/sinusoidal pattern comprised most of the "polypatterned" lesions, in which various combinations occurred. Immunohistochemically, mismatch repair protein deficiency was detected in 3 of the 22 cases studied, whereas 5 of the 33 patients with available follow-up had an internal malignancy/premalignancy. In conclusion, sebaceous neoplasms with organoid growth patterns are predominantly sebaceomas having a predilection for the scalp, occurring as solitary lesions in elderly patients (male to female ratio of 2:1). Such patterns are expected to be found in a quarter of sebaceomas. In most cases, more than one of the organoid patterns is present. These lesions do not appear to be associated with internal malignancy or mismatch repair deficiency in most cases. However, confirmation of the absence of any significant association with Muir-Torre syndrome syndrome will require genetic studies.

Peritumoral granulomatous reaction in endometrial carcinoma: association with DNA mismatch repair protein deficiency, particularly loss of PMS2 expression.

The observation of peritumoral granulomatous reactions (PGRs) in two endometrial carcinomas (ECs) with a PMS2-deficient/MLH1-intact expression pattern led us to investigate whether PGRs in EC were specifically associated with DNA mismatch repair (MMR) protein deficiency, particularly PMS2 loss. Hysterectomy specimens from 22 MMR protein-intact and 54 MMR protein-deficient ECs were reviewed with specific attention to the presence of a PGR and a tumour-associated lymphoid reaction [including tumour-infiltrating lymphocytes (TILs) and stromal lymphoid infiltrates]. The MMR protein-deficient ECs included 22 cases with combined MLH1/PMS2 loss, 11 with combined MSH2/MSH6 loss, 11 with isolated MSH6 loss, and 10 with PMS2 loss but intact MLH1 staining (including the two 'index' cases). Overall, PGRs were identified in seven of 54 (13%) MMR protein-deficient ECs, five of which showed a PMS2-deficient/MLH1-intact immunophenotype; three of these patients had germline PMS2 mutations and one additional patient had a germline MSH6 mutation. None of the MMR protein-intact tumours showed a PGR. Although five of the seven PGR-positive ECs had a high-grade histological component, six were stage I. Most ECs with PGRs also showed TILs and stromal lymphoid reactions, similarly to MMR protein-deficient ECs in general. MMR protein-deficient ECs, particularly those with PMS2 loss, occasionally show PGRs in addition to stromal lymphoid infiltrates and TILs. Therefore, PGRs could be considered to constitute a histological prompt for consideration of Lynch syndrome. The potential prognostic significance of PGRs in EC requires further study.

DNA mismatch repair protein deficient non-neoplastic colonic crypts: a novel indicator of Lynch syndrome

Lynch syndrome is the most common form of hereditary colorectal carcinoma. However, establishing the diagnosis of Lynch syndrome is challenging, and ancillary studies that distinguish between sporadic DNA mismatch repair (MMR) protein deficiency and Lynch syndrome are needed, particularly when germline mutation studies are inconclusive. The aim of this study was to determine if MMR protein-deficient non-neoplastic intestinal crypts can help distinguish between patients with and without Lynch syndrome. We evaluated the expression of MMR proteins in non-neoplastic intestinal mucosa obtained from colorectal surgical resection specimens from patients with Lynch syndrome-associated colorectal carcinoma (n = 52) and patients with colorectal carcinoma without evidence of Lynch syndrome (n = 70), including sporadic MMR protein-deficient colorectal carcinoma (n = 30), MMR protein proficient colorectal carcinoma (n = 30), and “Lynch-like” syndrome (n = 10). MMR protein-deficient non-neoplastic colonic crypts were identified in 19 of 122 (16%) patients. MMR protein-deficient colonic crypts were identified in 18 of 52 (35%) patients with Lynch syndrome compared to only 1 of 70 (1%) patients without Lynch syndrome (p < 0.001). This one patient had “Lynch-like” syndrome and harbored two MSH2-deficient non-neoplastic colonic crypts. MMR protein-deficient non-neoplastic colonic crypts were not identified in patients with sporadic MMR protein-deficient or MMR protein proficient colorectal carcinoma. Our findings suggest that MMR protein-deficient colonic crypts are a novel indicator of Lynch syndrome, and evaluation for MMR protein-deficient crypts may be a helpful addition to Lynch syndrome diagnostics.

P53 aberrations in low grade endometrioid carcinoma of the endometrium with nodal metastases: possible insights on pathogenesis discerned from immunohistochemistry

BackgroundTP53 mutations are rarely identified in low grade endometrioid carcinoma of the endometrium, and their pathogenic significance in such tumors is evidenced by the fact that TP53 aberrations have been associated with reduced recurrence-free survival in this subset of tumors. However, TP53 aberrations may not always represent a driving molecular event in a given endometrial cancer with a mutation. In this case study, the immunophenotype of a distinctive low grade endometrioid adenocarcinoma with an unusual pattern of lymph node metastases is used to explore the possible roles for underlying TP53-related molecular events in its pathogenesis.Case presentationA low grade endometrioid carcinoma, 9 cm in greatest dimension, with 35% invasion of the myometrial wall thickness, focal lymphovascular invasion, and metastases to 2 of 16 pelvic lymph nodes, was diagnosed in a 52-year-old woman. The endometrial tumor showed a p53-mutation (aberrant)-type immunohistochemical pattern in 40% of the tumor, but the rest of the tumor, as well as the foci of myometrial and lymphovascular invasion, were p53-wild type. Both lymph nodes with metastatic disease showed a distinct biphasic pattern, comprised of both p53-wild type and p53-aberrant areas in tumoral foci that were spatially apposed but not intermixed. Most p53-aberrant areas (at both the lymph nodes and the endometrium) showed a higher mitotic index and increased atypia as compared to the p53-wild type areas; both showed squamous differentiation. The p53-aberrant areas at both locations were also p16-diffusely positive, vimentin-positive, and estrogen/progesterone receptor-positive, whereas the p53-wild type areas showed an identical immunophenotype with the exception of being p16-mosaic positive. All components of the tumor at both the primary and metastatic sites showed loss of MSH2 and MSH6 and retained MLH/PMS2 expression.ConclusionsThe presence of p53-mutant and wild-type areas in multiple lymph nodes, coupled with the absence of a p53-aberrant immunophenotype in the myometrium-invasive or lymphovascular-invasive portions of the tumor, argues against the possibility that the TP53 mutation in this tumor is a driving event in its pathogenesis, at least regarding the metastatic process. This case illustrates how routine immunohistochemistry can provide important insights into underlying molecular events in cancers, exemplifies an uncommon co-existence of DNA mismatch repair protein deficiency and p53-aberrant immunophenotype in low-grade endometrioid carcinoma, illustrates morphologic differences between p53-aberrant and p53-wild type areas within in the same tumor, and is an exemplar of the emerging theory that lymph node metastases of endometrial cancer may be comprised of different subclones of the primary tumor.