Cholesterol Granulomas in a Great Plated Lizard, Gerrhosaurus Major Zoltan S
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Cholesterol Granulomas in a Great Plated Lizard, Gerrhosaurus major Zoltan S. Gyimesi1, DVM, Nancy L. Stedman2, DVM, PhD, Virginia R. Crossett1, RVT 1. Louisville Zoological Garden, 1100 Trevilian Way, Post Office Box 37250, Louisville, KY 40233, USA 2. Department of Veterinary Pathology, College of Veterinary Medicine, The University of Georgia, Athens, GA 30602, USA A bstr a c t: An adult female great plated lizard, Gerrhosaurus major, presented with anorexia, weight loss, dehydration, and central nervous system signs. After four weeks of unsuccessful therapy, the lizard was humanely euthanized. Gross pathologic examination revealed a large, granular, soft tissue mass compressing Downloaded from http://meridian.allenpress.com/jhms/article-pdf/12/3/36/2207584/1529-9651_12_3_36.pdf by guest on 28 September 2021 the brain. The mass was diagnosed histologically as a ventricular cholesterol granuloma. Cholesterol granulo mas were also present within the fat pad and ovary. The plasma cholesterol level in this plated lizard was elevated and was likely a predisposing factor. Intracranial cholesterol granuloma should be a differential for central nervous system signs in adult female reptiles, particularly those with concomitant hypercholes terolemia. K e y W o r d s : Plated lizard, Gerrhosaurus major, cholesterol granuloma, xanthomatosis, hypercholes terolemia. Biology - The genus Gerrhosaurus includes six species of compared to those of the green iguana, Iguana iguana (ISIS, plated lizards native to southern and eastern Africa. Plated 2001). The hemogram revealed a high normal leukocyte lizards are diurnal, terrestrial and are found in dry, rocky, count, eosinophilia (2.67 x 103 /pi, reference range = 0.54 +/- semi-open habitat (Rogner, 1997). These stout lizards have 1.00 x 103 /pi), basophilia (1.00 x 103 /pi), reference range = short limbs and a prominent lateral fold. They are oviparous 0.37 +/- 0.27 x 103 /pi), and azurophilia (3.67 x 103 /pi), refer and in the wild subsist on a variety of animals including ence range = 1.02 +/- 0.68 x 103 /pi), tfiasma biochemistries insects and gastropods, along with some plant material revealed hypoglycemia (glucose = 5.5 mmol/L, 99 mg/dl, ref (Rogner, 1997). The species in this report is the Sudan, or erence range = 187 +/- 53 mg/dl), hyperkalemia (potassium = great plated lizard, Gerrhosaurus major. 6.0 mmol/L, 6.0 mEq/L, reference range = 3.4 +/- 1.2 mEq/L), hyperchloridemia (chloride =136 mmol/L, 136 CASE REPORT mEq/L, reference range =117 +/- 7 mEq/L), and hyperpro- teinemia (total protein = 78 g/L, 7.8 g/dl, reference range = In October 2000, a 235 g adult female great plated lizard 6.1 +/- 1.2 g/dl). Fecal analysis revealed occasional coccidia was examined for lethargy and anorexia. The lizard had been and trichomonads. Coccidiosis was a chronic finding in this in the collection for over 11 years and was acquired as a juve group of lizards and previous treatment had failed to elimi nile. It was housed in a 1.79 m x 0.81 m x 0.42 m enclosure nate fecal shedding. with two adult conspecifics. The enclosure had a coarse sand A course of fenbendazole (Panacur®, 100 mg/ml, DPT substrate and flat rocks for hiding and basking. Artificial Laboratories, San Antonio, TX) at 50 mg/kg PO q 24 hr for 5 ultraviolet lighting was provided (Vita-Lite®, Duro-Test d, and sulfadimethoxine (Albon®, 50 mg/ml, Pfizer Animal Corp., Fairfield, NJ, and Verilux®, Verilux, Inc., Stamford, Health, Exton, PA) at 50 mg/kg PO q 24 hr for 7 d was pre CT) with a photoperiod of 12:12. The ambient temperature scribed for the endoparasitism. Empirical treatment was ranged from 27 - 35°C (80 - 95°F). The diet consisted of employed with ceftazidime (Fortaz®, 100 mg/ml, Glaxo neonatal mice, mealworms, and crickets. The crickets were Wellcome Inc., Research Triangle Park, NC) at 20 mg/kg IM gut-loaded with a commercial cricket chow (Ziegler™ q 72 hr. The plated lizard was supported with intracoelomic Cricket Diet, Zeigler Bros., Inc., Gardners, PA) and the diet fluid therapy including a combination of 5 ml non-lactated was supplemented weekly with calcium carbonate (Basic buffered electrolyte solution (Plasma-Lyte®, Baxter Drugs, Inc., Vandalia, OH) and multivitamins (Nekton®-Rep, Healthcare Corporation, Deerfield, IL), 5 ml of 5% dextrose Gunter Enderle, Pforzheim, Germany). (Abbott Laboratories, North Chicago, IL), and 0.5 ml of B At physical examination, the lizard would stargaze, had a vitamin complex (Phoenix Scientific, Inc., St. Joseph, MO) q stuporous mentation and a slow to absent righting reflex. The 72 hr. The animal’s clinical condition failed to improve after lizard exhibited a 30% loss in body weight compared to one four weeks of therapy. Due to the lack of response to treat historic weight from 1998. Whole body radiographs were ment, grave prognosis, and poor quality of life, the plated interpreted as normal. Blood was drawn from the ventral tail lizard was humanely euthanized. vein for analysis and banking. Reference ranges for blood Pathology - At post mortem examination, there were no parameters for this species are scant, so blood values were gross lesions. Representative tissue samples including the Journal of Herpetological Medicine and Surgery Volume 12, No. 3,2002 entire head were preserved in 10% neutral buffered formalin. rounding a ring of nuclei (Touton’s type). Infrequent clusters Tissues were sent to the Department of Veterinary Pathology of lymphocytes and rare heterophils were also present. The at The University of Georgia (UGA) for histopathologic eval granuloma was present within the lateral ventricle and uation. Upon arrival at UGA, the calvarium was removed. A expanded caudally. The ependymal lining of the ventricle was soft tissue mass measuring approximately 1 cm in diameter multifocally ulcerated and the granuloma compressed and occupied most of the cranial vault. The mass was roughly extended into the neuropil. The granuloma extended dorsal to spherical and light tan to off white with a granular texture. the optic tract and tectum, compressing both these structures. The mass severely compressed the caudal cerebral hemi The optic tract had severe multifocal myelin swelling adja spheres, tectum mesencephali, optic tracts, brainstem, and cent to the granuloma. A diagnosis of ventricular cholesterol cerebellum (Figure 1). granuloma with expansion into and compression of adjacent Histologically, the mass was a granuloma consisting of neural tissue was made. Similar cholesterol granulomas were dense sheets of epithelioid macrophages and multinucleate also detected histologically within the fat pad and ovary. Acid giant cells distended with intracytoplasmic lipid and promi fast and Lillie-Twort stains did not reveal any microorganisms nent extracellular cholesterol clefts (Figure 2). Giant cells had within any of the granulomas. Perl’s iron staining did not either haphazardly arranged nuclei, peripheral nuclei reveal any iron pigment within the cholesterol granulomas in (Langhans type), or rarely abundant foamy cytoplasm sur the cranial vault and fat pad, but multifocal iron pigment wasDownloaded from http://meridian.allenpress.com/jhms/article-pdf/12/3/36/2207584/1529-9651_12_3_36.pdf by guest on 28 September 2021 present within the ovarian cholesterol granuloma and else where in the ovarian interstitium. There were several maturing follicles at the periphery of the sections of ovary examined. Hepatocytes showed marked cytoplasmic lipid accumulation. DISCUSSION Cholesterol granulomas (xanthomas, xanthogranulomas) have been reported in humans (Muenchau and Laas, 1997), horses (Jackson, et al, 1994), dogs (Cox and Payne-Johnson, 1995), cats (Zanghi, et al, 1999), meerkats (Sladky, et al, 2000), birds (Latimer, 1994), reptiles (Schmidt and Hubbard, 1987, Gamer, et al, 1999), and amphibians (Russell, et al, 1990). These lesions are commonly found in the fourth and lateral ventricles of aged horses. In other species, the inci Figure 1. Brain; adult female great plated lizard, Gerrhosaurus dence is more sporadic. Cholesterol granulomas have been major. The cholesterol granuloma (CG) occupies most of the cra described in association with many sites including the choroid nial vault and lateral ventricle (LV), expanding into and plexus, meninges, oral cavity, middle ear, viscera, skin, and compressing most of the cerebral hemisphere (Ce). The optic around joints and long bones. In reptiles, these lesions have tract (Tr) and tectum (Te) ventral to the cholesterol granuloma been described most consistently within the central nervous are also compressed. system, but also the pulmonary parenchyma, eye, and coelomic cavity. They have been reported in lizards and a snake, with most of the lizard cases documented in several gecko species (Gamer, et al, 1999, Raiti and Gamer, 2000). The pathogenesis of these lesions is not completely under stood. During chronic or intermittent congestive hemorrhage, edema, and/or inflammation, cholesterol may be released from the membranes of damaged cells inducing a granuloma tous response. This is the likely cause of cholesterol granulomas seen in the ventricles of older horses (Jackson, et al, 1994). Although iron pigment was detected in the ovary of this plated lizard implying previous hemorrhage, the pigment was not consistently associated with cholesterol granuloma formation. Therefore, any relationship is uncertain. Hyperlipidemia and hypercholesterolemia, due to genetic, metabolic, or dietary factors, may also predispose to choles terol granuloma