Feline primary nonhematopoietic malignant liver tumors: A multicenter retrospective study (2000-2021).

There is scant literature on primary nonhematopoietic malignant liver tumors (PMLT) in cats. In this retrospective study, medical data of 40 cats diagnosed with PMLT were reviewed over a period of 22 years (2000-2021). The most frequent epithelial tumors were hepatocellular (42.5%) and bile duct carcinomas (32.5%), only six (15%) cats had mesenchymal tumors. The median age was 13 years and clinical signs commonly included ano-/hyporexia (62.5%), apathy/lethargy (52.5%), weight loss (42.5%) and vomiting (35%). At initial diagnosis, metastases were confirmed in 1 (2.5%) and suspected in three (7.5%) cats. Massive was the most frequent morphology (75%). Most intrahepatic tumors were left-sided (54.2%) with the left medial lobe being primarily affected (25%). Extrahepatic tumors were rare (5%). In 34 (85%) cats, liver lobectomy was performed (surgery group), four (10%) were treated palliatively (non-surgery group), and two (5%) received no treatment. Intraoperative complications occurred in 11.8% with four (15.4%) postoperative deaths. Recurrence was detected in 28.6% at a median of 151 days (range, 79-684 days), while postoperative metastases were suspected in 21.4% at a median of 186 days (range, 79-479 days). The median survival time (MST) was significantly longer in cats of the surgery group (375 days) than in the non-surgery group (16 days) (P = 0.002). MST was 868 days for hepatocellular compared to 270 days for bile duct carcinomas (P = 0.06). In summary, liver lobectomy is associated with prolonged survival times and good prognosis in cats with hepatocellular, and an acceptable prognosis in cats with bile duct carcinoma.