hepatoblastoma ), bile duct ( bile duct adenoma , bile duct carcinoma ), neuroendocrine ( carcinoid ) and mesenchymal ( hemangiosarcoma , leiomyosarcoma , fibrosarcoma ). 2-4 In dogs , malignant tumors are more common than in cats . Malignant tumors are further divided into 3 morphologic types : massive , nodular and diffuse . Massive liver tumors are large , solitary and typically involve a single liver lobe . Nodular tumors are multifocal masses that affect several liver lobes . Diffuse tumors encompass the entire or part of the liver with multifocal , coalescing nodules of diffuse involvement of the hepatic parenchyma . 2 , 3
The most common types of massive liver tumor in dogs are hepatocellular carcinoma ( HCC ) and hepatocellular adenoma ( HCA ). HCCs account for more than 50 % of primary liver tumor cases in dogs . 1 , 3 Bile duct carcinomas ( BDC ) are the second most frequent massive hepatic tumor in dogs accounting for 20 % of cases . 3 One study showed that 66 % of dogs with massive HCC had the largest mass in the left lateral lobe . The same study reported that 56 % of massive BDC also had the left lateral liver lobe as a preferred predilection site . 3 One study , showed that HCC if left untreated , had a median survival time ( MST ) of 270 days . However , MST for surgical resection of a massive HCC was not reached and it was greater than 1460 days . 8 Right sided HCC liver tumor was also considered a negative prognostic indicator .
Primary and nonhematopoietic hepatic sarcomas are rare in both dogs and cats . These tumors account for 13 % of all primary hepatic tumors . 3 Another study reported the prevalence of sarcomas to
Figure 3 : CT scan : Note large liver mass ( arrow ) pushing the gallbladder ( x ) to the left side of the abdominal wall . The stomach is indicated by (*)
be 3 % ( fibrosarcomas 2 %, leiomyosarcomas 1 %). 4 Diffuse morphology has not been reported , massive and nodular types make up 36 % and 64 % of sarcomas respectively . About 80 % of massive sarcomas were found in left lateral liver lobe , the remaining 20 % were in the right lateral . Hepatic sarcomas have an aggressive behavior . Metastatic disease occurred in 86 % -100% of the time . The preferred site for metastasis was reported to be spleen ( 57 %) followed by the regional lymph node ( 29 %) and then the lungs ( 14 %). 3 Gizmo ’ s splenic nodule continues to be static . No cytology or histopathology was performed , so it is still possible that it represents a metastatic lesion . However , given how aggressive sarcomas are , enlargement of the nodule over the past year would have been expected but this has not occurred .
The most common presenting clinical