Diagnostic Approach and Pathological Characterization of Metastatic Intrahepatic Cholangiocarcinoma in a Captive Puma (Puma concolor).

A 16-year-old captive male puma (Puma concolor) presented with progressive weight loss and acute mild gastrointestinal symptoms. Clinical examination, and diagnostic imaging revealed abdominal, pleural, and pericardial effusion and nodular masses in multiple organs. Due to the clinical condition, multiple organ involvement, and a poor prognosis, compassionate euthanasia was chosen. Necropsy revealed abundant cavitary effusions and multiple yellow-white neoplastic masses involving the left hepatic lobes. Metastatic nodules were observed throughout the peritoneum, pericardium, kidney, spleen, and spermatic cord. Histologically, the tumor was characterized by tubular and acinar structures embedded in a desmoplastic stroma. Neoplastic cells were positive for pan-cytokeratins (CKs), CK7, and, to a lesser extent, CK20. The gross, histologic, and immunohistochemical findings were consistent with intrahepatic metastatic cholangiocarcinoma.