Background and objective Signet ring cell carcinoma of the appendix (SRCCA) is an exceedingly rare tumor, and very limited data are available regarding its characteristics and survival probabilities. Our objective in this study was to utilize the Surveillance, Epidemiology, and End Results (SEER) database to explore the patient and tumor characteristics and to characterize the three-and five-year cancer-specific survival (CSS) probabilities of SRCCA. Methods Patients with SRCCA diagnosed between 2000 and 2015 were analyzed using the SEER database. The three-and five-year CSS probabilities were estimated by the Kaplan-Meier method, and the groups were compared using log-rank comparisons and multivariable Cox hazard regression analysis.

134 Background: High-frequency microsatellite instability (MSI-H) accounts for roughly 15% of all cases of colorectal cancer (CRC). Studies suggest a significant non-adherence to routine MSI testing in patients diagnosed with CRC despite universal guidelines. Methods: We used the NCDB to identify adults with MSI-H status CRC from 2010-2015 with the following histologic subtypes: mucinous and not otherwise specified adenocarcinoma, and medullary carcinoma. The primary site was localized to the right colon, left colon, and rectum; demographic factors, clinicopathologic features, and treatments were identified. Patients were stratified by site and discrete and continuous variable comparisons were made using the chi-square and Mann-Whitney test, respectively. Survival was examined with the Kaplan-Meier method and a Cox proportional hazards regression model. A logistic regression model was used to examine MSI status. All analyses were conducted with SAS version 9.4. Results: A total of 5364 patients were identified and stratified by site into 3 groups: right colon (n = 4004, 74.6%), left colon (n = 890, 16.59%) and rectum (n = 470, 8.76%). Compared to the left colon and rectum, right colon patients were more likely to be older females with larger tumors and less likely to receive chemoradiation. After adjusting for all else, we found statistical evidence that female vs. male gender (OR = 1.47; 95% CI: 1.24 to 1.73), Black vs. White race (OR = 0.61; 0.45 to 0.83), left vs. right colon (OR = 0.33, 0.27 to 0.41), rectum vs. right colon (OR = 0.08, 0.05 to 0.13), mucinous adenocarcinoma vs. adenocarcinoma (OR = 2.37, 1.92 to 2.93), medullary carcinoma vs. adenocarcinoma (OR = 8.86, 4.56 to 17.22), positive vs. negative k-RAS mutation (OR = 0.49, 0.41 to 0.59), and positive vs. negative CEA status (OR = 0.79, 0.66 to 0.94) were factors associated with MSI-H status. Improved survival was associated were Hispanic white race, stage 1, and free surgical margins within a multivariable context. Factors associated with poor survival: increased Charlson/Deyo score, advanced stage, lymphovascular invasion, and positive CEA status. Conclusions: In settings where resources are scarce and universal testing is not possible, there is a benefit from MSI testing in female patients, those with right-sided colon cancer, mucinous adenocarcinoma, and medullary carcinoma.

Background: Immunotherapy has revolutionized the treatment of cancer, but this has not come without a cost. Although immune checkpoint inhibitors are less toxic than conventional chemotherapy, they are associated with more frequent autoimmune side effects. Case presentation: We report a case of a patient with metastatic renal cell carcinoma who was treated with nivolumab and subsequently developed treatment related hypothyroidism with consequent rhabdomyolysis. Treatment with thyroxine resulted in resolution of the symptoms. Because of normal thyroid function tests before initiating nivolumab therapy and the absence of any other causes of hypothyroidism, it was safe to extrapolate a causal relationship between nivolumab and hypothyroidism. To date, this is the first reported case of a programmed cell death-1 inhibitor causing hypothyroidism, severe enough to induce rhabdomyolysis. Conclusion: Patients on nivolumab and other PD-1 inhibitors should be monitored and screened regularly for immune-related adverse events.

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Hemophagocytic lymphohistiocytosis is a syndrome characterized by excessive immune activation. Timely diagnosis can be challenging, and prompt treatment is the only hope for survival. We present an adult patient with a history of alcohol dependence, who presented with fatigue, bilateral lower extremity edema, and orange-colored urine. Clinical workup revealed abnormal liver function tests, elevated ferritin, cytopenia, and lymphadenopathy. Eventually, he was diagnosed with hemophagocytic lymphohistiocytosis. This case report encourages gastroenterologists to maintain a high index of suspicion when a patient presents with liver failure, hyperferritinemia, and cytopenia because they may be the first healthcare professionals to evaluate these patients.