Abstract / Summary
Malignant epithelioid peritoneal mesothelioma (MPeM) is a rare neoplasm arising from the mesothelial lining of the peritoneal cavity. Carbonic Anhydrase IX (CAIX) is a hypoxia-associated transmembrane enzyme commonly expressed in MPeM. A female patient with initial misdiagnosis of hepatocellular carcinoma received an imaging work-up, as part of the ELEGANCE clinical trial (NCT06735560). FDG PET-CT revealed intense hypermetabolism of the multilobar lesions in hepatic segment VIII, and diffuse anterior parietal peritoneal extension. [89Zr]Zr-girentuximab PET, a CAIX-targeting radiotracer, showed intense uptake of the hepatic lesion in segment VIII. A laparoscopy revealed adhesions in the right hypochondrium, throughout the subumbilical region and diffuse unresectable peritoneal carcinomatosis. The final histopathological diagnosis, after review of initial biopsy was MPeM. Immunohistochemical analysis revealed moderate to strong CAIX staining of tumor cells. To our knowledge, this is the first report of CAIX-targeted PET/CT in MPeM, supporting its potential role in innovative theranostic strategies.