Immune checkpoint blockade and thrombo-inflammatory remodeling in microsatellite instability-high intrahepatic cholangiocarcinoma with Trousseau syndrome: a case report.

Background: Cancer-associated thrombosis (CAT) is a major cause of morbidity and mortality in patients with malignancy and is increasingly recognized as a manifestation of tumor-associated thrombo-inflammation. Although immune checkpoint inhibitors (ICIs) have transformed the treatment of microsatellite instability-high (MSI-H) malignancies, their impact on the interplay between antitumor immunity and cancer-associated thrombosis remains poorly understood, particularly in intrahepatic cholangiocarcinoma (ICC). Case presentation: We report a 74-year-old woman with MSI-H intrahepatic cholangiocarcinoma presenting with Trousseau syndrome characterized by extensive arterial and venous thrombotic events, including deep vein thrombosis, portal vein thrombosis, multifocal cerebral infarctions, splenic infarction, and renal infarction. Following treatment with the PD-L1 inhibitor envafolimab in combination with rivaroxaban, radiographic evaluation demonstrated stable disease without recurrent thrombotic events. Longitudinal biomarker assessment revealed temporally associated reductions in circulating D-dimer and interleukin-6 (IL-6) concentrations during treatment, while peripheral immune-cell subsets exhibited dynamic changes that paralleled systemic inflammatory activity. Despite a temporary interruption of immunotherapy because of influenza A-associated pneumonia, both inflammatory and coagulation markers declined following resolution of the infection. Conclusion: This case underscores the complex interplay between systemic inflammation, coagulation activation, and tumor progression in MSI-H intrahepatic cholangiocarcinoma with Trousseau syndrome. Serial assessment of coagulation and inflammatory biomarkers may help characterize disease dynamics and inform individualized management.