Cholangiocarcinoma and hepatic myelolipoma incarcerated in a peritoneopericardial diaphragmatic hernia with pulmonary metastasis and carcinomatosis in a cat

CASE SUMMARY: A 14-year-old female neutered Persian-cross cat was presented with a 1 week history of anorexia and lethargy. On physical examination, marked tachypnoea and dyspnoea were evident. Radiographs of the thorax revealed a globoid-shaped cardiac silhouette with heterogeneous opacity consistent with a peritoneopericardial diaphragmatic hernia (PPDH), pulmonary nodules compatible with metastasis, seven sternal segments and a small liver in the cranial abdomen with loss of serosal detail. On echocardiography, there was no evidence of cardiac tamponade. Triple-phase CT angiography demonstrated a mixed soft tissue-, mineral- and fat-attenuated liver mass arising from the left hepatic lobes that showed a pronounced heterogeneous contrast-enhancement pattern within the pericardial sac, which was producing a marked mass effect on the adjacent structures. Additionally, there was an increase in attenuation of the mesenteric fat and peritoneal effusion. The pulmonary nodules were confirmed. Imaging findings were compatible with a malignant hepatic neoplasia incarcerated in a PPDH, lung metastasis and carcinomatosis. Owing to the poor prognosis, the cat was humanely euthanased. Histopathological diagnosis was cholangiocellular carcinoma and hepatic myelolipoma, pulmonary metastasis and carcinomatosis. RELEVANCE AND NOVEL INFORMATION: Hepatic cholangiocarcinoma incarcerated in a PPDH with pulmonary metastasis and carcinomatosis has not been previously described. Suspicion of a hepatic neoplasia should be raised in cases of PPDH and pulmonary nodules.