Spontaneously occurring hepatocellular neoplasia in adolescent cynomolgus monkeys (Macaca fascicularis)

Hepatocellular carcinomas in captive prosimians

We performed a retrospective examination of spontaneous hepatocellular carcinomas (HCCs) (primary and metastatic tumors) in 14 captive prosimians brought to the Veterinary Medical Diagnostic Laboratory in North Carolina State University over a period of 11 years (2003 to 2014) to characterize the tumors. These animals are endangered primates; a better understanding of the main fatal neoplasms is crucial. In addition to the histologic evaluation, an immunohistochemical study was also performed, using a hepatocyte marker (hepatocyte paraffin 1 [HepPar-1]) and 2 cholangiocyte markers (keratin 7 [K7] and keratin 19 [K19]), in an attempt to identify a specific profile for HCCs with metastatic behavior. Six of the 14 HCCs had pulmonary metastases. The most frequent histopathological findings were a trabecular pattern (14/14, 100%), presence of multinucleated cells (12/14, 85.7%), and foci of extramedullary hematopoiesis (9/14, 64.3%). The mitotic count was significantly higher in the metastatic HCCs (P < .05). HepPar-1 was detected in all primary and metastatic HCCs, with a strong intensity of staining. Labeling for K7 and K19 was positive in 12 HCCs (85.7%) and 1 HCC (7.1%), respectively. Contrary to the less aggressive HCCs, most of the metastatic HCCs (5/6) expressed K7 in more than 15% of cells. The percentage of K7-positive neoplastic hepatocytes was significantly higher in metastatic HCCs. This study suggests that K7 might be a prognostically relevant marker in HCCs of captive prosimians.

Aberrant Expression of Cell Cycle Regulator 14-3-3-σ and E-Cadherin in a Metastatic Cholangiocarcinoma in a Vervet Monkey (Chlorocebus pygerythrus)

We present a unique case of metastatic cholangiocarcinoma with concurrent abdominal cestodiasis in an African green monkey (Chlorocebus pygerythrus) that presented with respiratory insufficiency and abdominal discomfort. There were multiple white-grey masses in the liver and colonic serosa alongside intra-abdominal parasitic cysts. Histopathologically, the liver masses were composed of poorly-differentiated epithelial cells that formed densely cellular solid areas and trabeculae. The neoplastic cells were strongly immunopositive for CK7 but negative for Hep-Par1 antigen, which confirmed a diagnosis of cholangiocarcinoma. Interestingly, there was strong and diffuse neoexpression in the tumour of the cell cycle regulator 14-3-3σ, which is not constitutively expressed in normal liver. There was aberrantly strong expression of E-cadherin, a key cell-cell adhesion protein, in neoplastic cells with evidence of cytoplasmic internalization. This is the first immunohistochemical analysis of 14-3-3σ and E-cadherin in a liver neoplasm in an animal species and the use of these markers requires further investigation in animal liver neoplasms.

Superparamagnetic Iron Oxide-enhanced Magnetic Resonance Imaging of Spontaneous Hepatic Neoplasia in a Cynomolgus Macaque (Macaca fascicularis)

Although the number of reports describing tumors in aged NHP has increased, spontaneous neoplasias in NHP are extremely rare, with the notable exception of prosimians, in which spontaneous hepatic neoplasms arise. In addition to radiography and ultrasonography, superparamagnetic iron oxide (SPIO)-enhanced MRI tends to be applied in human practice to non-invasively locate, identify, and size liver tumors and to define the border between neoplastic and normal tissues. Here we report a 13-y-old female cynomolgus monkey with anorexia and serologically normal liver enzymes. After fluid therapy, the condition remained in remission for several months. Later, however, a palpable mass was assessed by using ultrasonography, radiology, and SPIO-MRI; T2-weighted images revealed a clear border between a hepatocellular carcinoma and normal liver tissue. Findings at necropsy supported the imaging data. Serologic assessment after euthanasia revealed a positive reaction to an abnormal form of prothrombin (PIVKA-II). We recommend SPIO-MRI as a practical and useful for diagnosing hepatocellular neoplasias in NHP. This study is the first to demonstrate the applicability of SPIO-MRI for the identification of hepatocellular carcinoma in NHP.

Hepatocellular carcinoma in two captive golden-headed lion tamarins (Leontopithecus chrysomelas)

Two cases of hepatocellular carcinoma (HCC) in 2 female captive golden-headed lion tamarins (Leontopithecus chrysomelas) are described. HCC was diagnosed in both, with pulmonary metastasis in one of them. Neoplastic cells were positive for hepatocyte-specific antigen (HSA) by immunohistochemistry, confirming the diagnosis.

Hepatocellular carcinoma with intracranial metastasis in a Japanese macaque (Macaca fuscata)

BACKGROUND

A 23-year-old male Japanese macaque (Macaca fuscata) showed left ptosis, which progressed to exophthalmos.

METHODS

The macaque underwent a clinical examination, CT and MRI, and was euthanized. Necropsy and histopathological examination were performed after euthanasia.

RESULTS

The CT revealed and MRI confirmed an intracranial mass at the skull base with orbital extension. At necropsy, there were a large hepatic mass and an intracranial mass compressing the left temporal lobe of the brain. Histopathological and immunohistological examinations revealed that the masses were hepatocellular carcinoma (HCC) and a metastatic lesion. In both the primary and metastatic lesions, neoplastic hepatocytes were arranged mainly in a trabecular pattern. Immunohistochemically, the tumor cells were positive for cytokeratin (AE1/AE3 and CAM5.2) and hepatocyte paraffin 1 and negative for cytokeratin 7 and 20 and vimentin.

CONCLUSION

To our knowledge, this is the first case report of HCC with intracranial metastasis in a macaque.

Spontaneous and Drug-Induced Hepatic Pathology of the Laboratory Beagle Dog, the Cynomolgus Macaque and the Marmoset

This review focuses on the background hepatic pathology present in three of the most commonly used species in the safety assessment of drugs, namely the beagle dog, the marmoset and the cynomolgus macaque. Both the nonneoplastic and neoplastic pathology are reviewed with a discussion on the potential impact that significant background pathology might have on the interpretation of any drug-induced pathology during subsequent testing. Although specific instances, such as parasitological infection in wild-caught primates can pose problems of interpretation, in general the background pathology in both the dog and the nonhuman primates, is not significantly different from that seen in the liver of laboratory rodents and with experience should not pose significant problems for the experienced pathologist. The relative merits of the primate versus the dog as a choice of second species are also considered in some detail. Although there is an inbuilt prejudice that the primate will more closely mimic subsequent effects that might occur in man in the clinic, insofar as the liver is concerned, there are many instances where the dog has been more representative of human exposure and metabolism and there is little evidence to show that the nonhuman primate is consistently better than dog in predicting human liver toxicity. As with most areas of science, comparative toxicology would dictate that the more information gained, from as wide a range of species as is practical, will give the best assessment for any subsequent problems in the clinic. This pragmatic approach should prove to be more successful than one based entirely upon an assumption, and in many cases the assumption is incorrect, that the primate always predicts human toxicity better than the nonprimate, including the dog.

Well-differentiated hepatocellular carcinoma in a ring-tailed lemur (Lemur catta)

A 16-year-old male ring-tailed lemur (Lemur catta) was presented with severe cachexia and an abdominal mass. The encapsulated, multilobular mass replaced the right medial lobe of the liver and compressed the adjacent gall bladder. Multiple haemorrhages and necrotic foci were found within the mass. Microscopically, neoplastic cells formed cords of moderately pleomorphic, polygonal cells with mild to moderate anaplasia. Immunohistochemical markers used for diagnosis of hepatocellular carcinomas in man were used to characterize the neoplastic cells, which expressed hepatocyte-specific antigen, but not glypican-3 or polyclonal carcinoembryonic antigen. Gross, microscopical and immunohistochemical features of the tumour were most consistent with a well-differentiated hepatocellular carcinoma. Although this tumour is common among prosimians, to the authors' knowledge this is the first documented case in a ring-tailed lemur. Hepatocellular carcinomas have been associated with hepatitis virus infections and excessive hepatic iron in man; however, no association was established between this tumour and viral infection or hepatic iron storage disease in the present case.

Focal nodular hyperplasia in the livers of cynomolgus macaques (macaca fascicularis)

Two cases of spontaneous focal hepatic hyperplasia were observed in young female cynomolgus macaques (Macaca fascicularis). Grossly, a single raised nodule was observed in the left hepatic lobe. Histopathologically, the nodule compressed surrounding normal tissue; however, the hepatic cords within the nodule continued to those in the nor mal area except in part. Extensive fibrosis and absence of a normal hepatic triad were observed in the nodule. Thin fibrous septa radiating from the dense central stellate scarring and distended vessels were apparent in one animal. Hepatocytes in the nodule lacked cellular atypia, showed frequent PAS-positive eosinophilic inclusions in the cytoplasm and showed higher positive ratios for PCNA. The present cases resembled focal nodular hyperplasia reported in humans and a chimpanzee.

H-ras consensus sequence and mutations in primary hepatocellular carcinomas of lemurs and lorises

The authors have determined a consensus sequence for exons 1 and 2 of H-ras from captive lemurs and lorises and evaluated samples of nonneoplastic liver and hepatocellular carcinomas (HCC) from affected animals for mutations in these exons. Frozen liver samples were collected from 20 animals representing 9 different species with a sex distribution of 10 males and 10 females. A total of 26 liver samples, including 11 normal livers, 9 HCC, and 6 samples from nonneoplastic regions of liver from animals with HCC, were evaluated. This is the first report of the consensus sequence for exons 1 and 2 of H-ras in prosimians, and the authors have determined that it is identical to that of human H-ras and differs only slightly from the chimpanzee sequence. Point mutations were identified in 6 of the 9 HCC samples examined with codons 7, 22, 32, 56, 61, 84, and 96 affected. Two carcinomas had double mutations, and one tumor had triple mutations. One HCC had a mutation in codon 61, which is identical to a recognized affected codon for an H-ras "hot spot" in rodent neoplasia that has also been reported in human tumors. Although not statistically different, metastasis occurred in 5 of 6 HCC with H-ras mutation and only 1 of 3 HCC without mutations. There were 4 silent mutations that did not contain changes in the encoded amino acids, 2 of which were found in nonneoplastic regions of tumor-bearing liver.

Combined hepatocellular-cholangiocarcinoma in a lesser flamingo (Phoenicopterus minor)

A case of combined hepatocellular-cholangiocarcinoma (CHCC) in an adult male lesser flamingo (Phoenicopterus minor) that was part of a breeding programme at a private facility is reported. Grossly, the liver was markedly enlarged with multifocal, well-circumscribed, pinpoint to 2 cm diameter pale tan nodular masses. Histologically, the hepatic parenchyma was replaced by neoplastic cells that demonstrated hepatocellular and, less frequently, biliary epithelial cell differentiation. Positive pan-cytokeratin (AE1/AE3/PCK26) immunolabelling of the neoplastic cells forming bile ducts with the scattered immunoreactivity of cells forming glandular structures within the areas of hepatocellular differentiation supported the diagnosis. No metastases were detected. CHCC is a rare neoplasm in mammals and birds. This is the first report where gross, histological, and immunohistochemical characteristics of CHCC in a bird are described, and the first report of CHCC in a lesser flamingo.

Spontaneous neoplasms observed in cynomolgus monkeys (Macaca fascicularis) during a 15-year period

A total of 33 tumors were observed during a time period of 15 years (1992-2006) in cynomolgus monkeys. The great majority of neoplasms was benign (23 benign neoplasms versus 10 malignant tumors). Fourteen appeared in males and 19 in females. The age of tumor-bearing animals ranged between 2 years 2 months and 13 years 9 months. Most of the tumors (22) in the cynomolgus monkeys were seen in endocrine organs (adrenal cortical adenoma, adrenal hemangioma, C-cell carcinoma, follicular adenoma), respiratory system (nasal cavity adenoma, pulmonary squamous cell carcinoma, bronchio-alveolar carcinoma, bronchiolar papilloma, chondromatous hamartoma) and female genital system (uterine polyp, uterine adenoma, uterine leiomyoma and teratoma of the ovary). Four animals revealed malignant lymphoma infiltrating multiple organs.

Spontaneous peritoneal malignant mesothelioma in a geriatric japanese macaque (Macaca fuscata)

A 28.5-year-old female Japanese macaque (Macaca fuscata) was euthanatized because of abdominal distension due to severe ascites. Nodular lesions of varying sizes up to 5 mm in diameter were distributed diffusely on the surface of the omentum, mesentery and parietal peritoneum. No neoplastic masses were detected in any visceral organ. The nodules were composed of proliferation of mono- or multi-layered epithelial-like cells occasionally showing papillary growth and sheets of small round or polygonal cells. Signet ring-like cells and tubular structures were occasionally present. Neoplastic cells were strongly positive to cytokeratin, and occasionally to vimentin. Based on gross and histopathological findings, this tumor was diagnosed as an epithelial type of peritoneal malignant mesothelioma, the first reported case in the non-human primates.

A case report of hepatocellular carcinoma and focal nodular hyperplasia with a myelolipoma in two chimpanzees and a review of spontaneous hepatobiliary tumors in non-human primates

Spontaneous hepatobiliary tumors in non-human primates are uncommon. Here we report a case of hepatic carcinoma and a case of hepatic focal nodular hyperplasia (FNH) and myelolipoma in two captive chimpanzees. A 16-year-old male chimpanzee (4X0392) died after an 8-month history of hepatic amyloidosis and low-grade anemia. Necropsy findings included a hepatic neoplasm with highly pleomorphic hepatocytes arranged into irregular thickened trabeculae. The diagnosis was high-grade hepatocellular carcinoma. A second male chimpanzee (4X0080), 23 years of age, died suddenly of heart failure secondary to cardiomyopathy. An incidental finding at necropsy was a liver mass characterized by multinodularity, prominent fibrous septa, and biliary hyperplasia. These features were consistent with FNH. While 4X0392 had no history of experimental viral exposure, 4X0080 was vaccinated with inactivated hepatitis B virus, an attenuated hepatitis A virus, and was experimentally infected with hepatitis C virus and human immunodeficiency virus. A survey of the literature revealed 68 reported cases of hepatobiliary tumors in non-human primates, including 12 hepatocellular adenomas, eight cholangiocellular adenomas/cystadenomas, 22 hepatocellular carcinomas, seven cholangiocarcinomas, and seven gallbladder adenocarcinomas. The majority of reported cases have been in prosimians and Old World monkeys. Hepatic neoplasia is rare in chimpanzees. Only four hepatic neoplasms have been reported in chimpanzees, three of which were associated with viral hepatitis. FNH has not been previously described in any non-human primate.