A clear cell hepatocellular carcinoma in an obese dog with hyperlipidemia: a case report

Abstract

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial license (http://creativecommons. org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Clear cell hepatocellular carcinoma (CCHCC) is a rare subtype of hepatic tumors that occur in less than 10% of dogs and is extremely rare in cats [1]. Histologically, the CCHCC comprises well-differentiated hepatocytes with vacuolated cytoplasm in hematoxylin and eosin (H&E) stained section. Generally, the vacuoles represent intracytoplasmic accumulation of glycogen and/or lipids [2,3]. In human medicine, CCHCC is considered as a low-grade malignancy with a favorable prognosis, which is unique when compared to other subtypes of hepatocellular carcinoma (HCC) [4,5]. However, in veterinary medicine, the incidence of CCHCC is rare, and thus clinical features of CCHCC have not been fully characterized. Here we describe the cytological, histological, and clinical aspects of CCHCC in a dog with obesity and hyperlipidemia. An 11-year-old spayed female mixed-breed dog weighing 7.5 kg presented to a local hospital with elevated liver enzymes and increased total cholesterol levels (450 mg/dL; RI, 112 to 312 mg/dL). There was no evidence of other underlying diseases based on the exam. The patient received liver supplements for 1 month, but the liver enzyme levels remained high. After 2 months, the patient was referred to Seoul National University Veterinary Medical Teaching Hospital (SNUVMTH) for further evaluation. At the time of admission to SNU-VMTH, the patient had no observable clinical signs. On physical examination, no remarkable findings were detected except that the body condition score (BCS) was 8/9. The complete blood count (ADVIA2120i; Siemens Healthcare GmbH, Germany) showed mild thrombocytosis (70.4 × 10/μL; RI, 14.3 to 40.0 × 10/μL) and An 11-year-old obese dog was referred for a liver mass. Cytologic examination revealed vacuolated hepatocytes with mild pleomorphism. A partial liver lobectomy was performed. On histopathologic examination, the mass was diagnosed as hepatocellular carcinoma composed of hepatocytes with clear vacuoles. These findings were consistent with clear cell hepatocellular carcinoma (CCHCC). The CCHCC is a rare subtype of hepatocellular carcinoma in dogs, and clinical features are poorly defined. This is the first report on the cytological, histological and clinical aspects of CCHCC, suggesting that obesity and hyperlipidemia are potential risk factors for CCHCC in dogs.