Cholesterol Granulomas in a Great Plated , 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 , 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 Gerrhosaurus includes six of compared to those of the green iguana, Iguana iguana (ISIS, plated 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 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 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 formation. Circulating cholesterol and triglyceride levels were determined on banked plasma from the plated lizard in this report after the cause of death was Figure 2. Brain; adult female great plated lizard, Gerrhosaurus diagnosed. Compared to approximate reference ranges major. The cholesterol granuloma consists of numerous extracel­ (Divers and Cooper, 2000), plasma cholesterol was moderately lular cholesterol clefts (arrows) surrounded by foamy, epithelioid elevated (21.9 mmol/L, 847 mg/dl, reference range = 0.6-6.0 macrophages with frequent giant cell formation (arrowheads). mmol/L) while triglyceride levels were interpreted as normal H&E. Bar = 30 pm. (0.6 mmol/L, 56 mg/dl, reference range = 0.6-6.0 mmol/L).

Volume 12, No. 3,2002 Journal of Herpetological Medicine and Surgery 37 Vitellogenesis has been associated with elevations in circulat­ Lipid can leak from the vasculature of the choroid plexus ing cholesterol in reptiles. The hypercholesterolemia in this allowing cholesterol to precipitate out into extracellular crys­ plated lizard may have been secondary to the active ovarian tals, inducing a foreign body reaction and granuloma folliculogenesis confirmed microscopically. formation. The intracranial granuloma in this plated lizard Rabbits fed a high lipid diet are reported to be predisposed was within the lateral ventricle supporting the presumption to developing cholesterol granulomas of the choroid plexus that the lesion began in the choroid plexus. (Muenchau and Laas, 1997). High levels of dietary saturated Cholesterol granulomas are not neoplasms, but they can be fat and cholesterol, as well as lack of exercise, may have con­ locally invasive. In a recent report, a cholesterol granuloma in tributed to the hypercholesterolemia seen in this case also. a meerkat invaded the cerebrum and calvarium (Sladky, et al, Neonatal mice were a significant component of the plated 2000). In this plated lizard, evidence of expansion into the lizard captive diet and are relatively high in cholesterol cerebral neuropil was present. The marked hepatic lipidosis in (Crissey, etal, 1999). this lizard may have been a consequence of long term anorex­ Other factors may influence circulating levels of cholesterol. ia and/or active folliculogenesis. During normal follicle In humans, cholesterol levels tend to increase with age, partic­ maturation in reptiles, the liver will swell under the influence ularly during the time of peak weight gain (20 - 50 years old) of estrogen as it processes vitellogenin from the fat stores of the body (DeNardo, 1996).

(Grundy, 1999). One study in Suwannee river cooters, 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 Pseudemys concinna suwanniensis, demonstrated a progres­ Antemortem diagnosis of an intracranial cholesterol granu­ sive rise in serum cholesterol with increase in age (size) loma is very difficult. History, gender, and the presence of (Jackson, et al, 1970). Perhaps this trend occurs in other rep­ central nervous system signs and hypercholesterolemia may tile species. Genetic background influences blood cholesterol aid development of a presumptive diagnosis. Advanced imag­ levels in humans (Grundy, 1999). Genetics may play a role in ing modalities such as magnetic resonance imaging and regulating reptile blood cholesterol levels also, but this has not computed tomography may be useful. Currently, treatment of been evaluated. intracranial cholesterol granulomas is challenging and limited In most taxa, a gender predisposition for cholesterol granu­ to surgical excision. Anecdotal reports suggest some cuta­ loma occurrence has not been established. In humans however, neous lesions in birds are responsive to thyroid hormone and cholesterol granulomas of the choroid plexus appear to occur may shrink with L-thyroxine supplementation (Perry, et al, more commonly in males (Muenchau and Laas, 1997). In rep­ 1991). It is unknown whether this therapy has any value in tiles and amphibians, a female predisposition has been non-cutaneous cholesterol granulomas. observed. This case further supports the hypothesis that in rep­ tiles and amphibians, physiologic hypercholesterolemia ACKNOWLEDGEMENTS associated with ovarian follicular development may predispose to cholesterol granuloma formation in certain individuals. We thank Dr. Roy Burns, Elizabeth Hayden, and Bill The choroid plexus constitutes a vascular fenestrated capil­ McMahan and the rest of the herpetological staff at the lary endothelium unprotected by the blood brain barrier. Louisville Zoo for their assistance and support. Consequently, it is the target for numerous systemic disorders (Levine, 1987), including cholesterol granuloma formation.

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