Islet Cell Tumor in a Savannah Monitor (Varanus exanthematicus)
A 7.5-year-old captive born Savannah monitor, Varanus exanthematicus, presented with lethargy, anorexia, constipation, and narcolepsy-like behavior. Plasma biochemical analysis demonstrated mildly elevated liver enzymes, hypercalcemia, and hypoproteinemia. Coelomic ultrasound revealed multiple echolucent and rare echogenic round hepatic structures. Diagnostic coelioscopy was attempted but limited by anesthetic complications and varanid anatomy. Although it could not be confirmed during surgery, clinical signs and blood work supported hepatic disease. Because of progression and severity of clinical signs, the monitor was humanely euthanized. Further histopathologic evaluation revealed a pancreatic islet cell tumor with hepatic metastases and multifocal hepatic cholangiocarcinomas. Insulin immunoassay values were used post-mortem in this case and may be useful for diagnosis of insulinoma in reptiles. To the authors' knowledge, this is the first report of a reptile with functional islet cell neoplasia that demonstrated clinical illness and elevated insulin levels.ABSTRACT
Ultrasonograph of a Savannah monitor lizard liver with metastatic islet cell tumors and cholangiocarcinoma. GB = gall bladder, CY = hepatic cyst, CC = cholangiocarcinoma.
Liver and pancreas resected from a Savannah monitor. Within the right lobe is a cholangiocarcinoma (solid white arrow). There are multiple insulinomas both within the right liver lobe and pancreas (dotted white arrows). In the left lobe, there are multiple, poorly demarcated hepatic cysts (white circle).
Histopathologic examination of a pancreatic islet cell tumor. Packets of polygonal neoplastic cells surrounded by a moderately dense fibrovascular stroma. There is peripheral and perivascular palisading of neoplastic cells.
Histopathologic examination of a hepatic cholangiocarcinoma. Widely spaced tubules of neoplastic cuboidal epithelial cells (black arrow) embedded within dense collagenous tissue.
