
Joint Pathology Center Veterinary Pathology Services WEDNESDAY SLIDE CONFERENCE 2013-2014 Conference 19 19 March 2014 CASE I: No label (JPC 4004355). noted to have buphthalmia of the right eye and had multiple foci of white tissue within the Signalment: 1-year-old intact female Sprague- anterior chamber, in addition to a Y-shaped band Dawley rat, (Rattus norvegicus). of tissue (2mm in diameter) present within the posterior chamber. The vasculature surrounding History: A one-year-old intact female the pupil was prominent and the anterior chamber experimentally naïve Sprague-Dawley rat was cloudy. Apart from the ocular lesion, the (NTac:SD) used as a soiled bedding sentinel was animal appeared to be in good health. The animal 1-1. Eye, SD rat: The right eye was bupthalmic and had multiple foci of 1-2. Eye, SD rat: The affected eye on right shows a marked protein white tissue within the anterior chamber in addition to a Y-shaped band effusion filling the anterior chamber as well as a posterior synechia and of tissue (2mm in diameter) present within the posterior chamber. The mineralization subjacent to the lens capsule. Normal eye at left for vasculature surrounding the pupil was prominent and the anterior comparison. (HE 0.63X) chamber was cloudy. (Photo courtesy of: Laboratory of Comparative Pathology, Memorial Sloan Kettering Cancer Center, 1275 York Av Box 270, New York, NY 10065) 1 WSC 2013-2014 was monitored and the lesion showed no signs of posterior chamber that are bordered by cyclitic progression. The animal was later euthanized for membranes are filled with eosinophilic routine sentinel testing. homogenous proteinaceous fluid. Gross Pathology: Gross lesions were observed The anterior chamber is filled with eosinophilic in the right eye, as described in the history. No homogenous proteinaceous fluid (plasmoid other gross changes were observed on complete aqueous). necropsy. Left eye (section not provided): Within normal Histopathologic Description: Right eye: The limits. lens is misshapen and has a wrinkled capsule. Multifocally extensive areas of loss of sub- Contributor’s Morphologic Diagnosis: Right capsular lenticular fibers (both on anterior and eye: posterior surfaces) and replacement by 1. Marked panuveitis, lymphocytic, with posterior mineralized debris are evident. Lenticular synechiae and cyclitic membranes, chronic. epithelium is hyperplastic and there is migration 2. Hypermature cataract, subcapsular, chronic. of epithelium to the posterior lens surface. 3. Retina: Marked retinal atrophy, chronic. Several lenticular epithelial cells are spindle- shaped (fibrous metaplasia). Contributor’s Comment: Histopathological changes in the right eye are consistent with Multifocal adhesions between the lens and advanced cataract, and other changes within the posterior surface of the iris (posterior synechiae) eye suggest phacolysis (lens protein leakage) are present. Extensive fibrovascular membranes leading to secondary uveitis (phacolytic uveitis). are present and are adhered to the ciliary body, The pathogenesis is suspected to be leakage of posterior lens capsule, and choroid (cyclitic lenticular protein from the lens (even with intact membranes). The retina shows full thickness lens capsule) leading to uveal inflammation. atrophy. The iris shows mild vascular congestion. Predominant lymphocytic uveitis present in this The iris, ciliary body and choroid are thickened case is also consistent with phacolysis leading to by fibroplasia and an inflammatory infiltrate secondary uveitis. The Y-shaped macroscopic composed of numerous lymphocytes, and appearance of the aforementioned cataract is moderate numbers of plasma cells, eosinophils, similar to the congenital sutural cataract that neutrophils and hemosiderin-laden macrophages, occurs along the suture lines of the lens in humans with multifocal formation of lymphocytic and may also be observed as a late change in aggregates in the choroid. Remnant spaces in the advanced cataracts of other etiologies. Although 1-3. Eye, SD rat: Higher magnification of the adherence of the iris to the 1-4. Eye, SD rat: The lens is in direct apposition to the retina at right. At lens capsule (posterior synechia) (small arrows) as well as loss of left, the vitreous is markedly diminished and there is severe full thickness subcapsular lens fibers with replacement by mineralized debris. (Large retinal atrophy (arrows). Underneath the wrinkled lens capsule, there is arrows). (HE 41X) fibrous metaplasia of lens fibers adjacent to areas of mineralization. 2 WSC 2013-2014 suture lines are present in both anterior and lens fiber formation), lens epithelial hyperplasia posterior lens capsules, it is the posterior capsular and/or posterior migration of lens epithelium suture lines that manifest a characteristic Y-shape (occasionally followed by fibrous metaplasia), grossly when cataract forms along its margins. and mineralization. Hypermature cataracts often Some forms of non-congenital mature cataracts exhibit residual nuclei within lakes of can progress along suture lines. proteinaceous fluid, surrounded by a wrinkled capsule. Cataracts can be inherited (i.e. familial Cataracts are commonly associated with aging in cataracts in dogs) or secondary to anatomic various strains, including Sprague-Dawley (SD) anterior segment anomalies; formation may also rats. No sex predilection for the development of be induced by a variety of stimuli, including solar cataracts has been reported in the literature. (or other) irradiation, cold, increased intraocular Capsular cataracts, specifically posterior sub- pressure, toxins, nutritional derangements, local capsular cataracts, are noted with increasing inflammation and direct trauma. Most cataracts incidence starting at week 57 of age in SD rats encountered within veterinary medicine are (Week 57- 2.7%, Week 83- 8.5% and Week 110- classified as inherited, post-inflammatory or 13.4%).1 Diffuse opacification of the lens along idiopathic; however, cataract formation due to the posterior suture lines has also been reported in canine diabetes, galactose accumulation in this strain.1 Anterior cortical striations that can kangaroos and wallabies raised on cow’s milk, eventually progress to senile cataracts are arginine deficiency in puppies, wolf cubs, or commonly seen in SD rats between 83 and 110 kittens on milk replacer, dietary deficiencies (in weeks.1 It is interesting to note that this case has sulfur-containing amino acids, zinc or vitamin C) hypermature cataract in both anterior and or solar irradiation in farmed fish and posterior subcapsular regions. It is difficult to administration of the aminoglycoside hygromycin ascertain the region where the cataract first B in sows, have also been described, although the started. However, based on the reported age- pathogenesis of these examples is not necessarily based incidence, it is speculated that the posterior fully elucidated.4 Additionally, as noted by the subcapsular region is the first site of cataract contributor, cataract formation is a common age- formation. It is also possible that both anterior and related change in several strains of rats. posterior regions co-evolved the cataractous change independently of one another. In this case, we concur with the contributor’s comprehensive histological description as well as Approximately 3-4% of Sprague-Dawley rats the proposed pathogenesis. The formation of age- have minor lens lesions comprised of foci of induced cataracts likely resulted in lens protein swollen or degenerate lens fibers starting as early leakage (phacolysis), with subsequent phacolytic as 19-20 days of gestation and these may uveitis, occlusion of the drainage angle, increased represent early changes that may eventually lead intraocular pressure, glaucoma and eventually, to cataract.2 Glaucoma has been described as a full thickness retinal atrophy. complication of advanced cataracts in rats, and the proposed pathogenesis was lens-induced Contributing Institution: Laboratory of uveitis.3 Comparative Pathology MSKCC JPC Diagnosis: E y e : U v e i t i s , 1275 York Av Box 270 lymphoplasmacytic, chronic, diffuse, severe, with New York, NY 10065 cataract formation, drainage angle occlusion, and posterior synechiae. References: 1. Taradach C, Regnier B, Perraud J. Eye lesions Conference Comment: Cataract is the most in Sprague-Dawley rats: type and incidence in common lens disorder in any domestic species; it relation to age. Lab Anim. 1981;15(3):285-287. can be distinguished microscopically from 2. Taradach C, Greaves P. Spontaneous eye fixation/sectioning artifact by (in order of lesions in laboratory animals: incidence in occurrence) detection of Morgagnian globules relation to age. Crit Rev Toxicol. 1984;12(2): (eosinophilic globules of denatured lens protein), 121-147. bladder cells (large, foamy nucleated cells that 3. Wegener A, Kaegler M, Stinn W. Frequency may represent abortive epithelial attempts at new and nature of spontaneous age-related eye lesions 3 WSC 2013-2014 observed in a 2-year inhalation toxicity study in rats. Ophthalmic Res. 2002; 4:281-287. 4. Wilcock BP. Eye and ear. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 1. 5th ed. Philadelphia, PA: Elsevier; 2007:494-497. 4 WSC 2013-2014 CASE II: E3236/07 (JPC 3164800). especially in extrabulbar parts of the mass are foci of myxoid, cartilaginous or osseous metaplasia. Signalment: 8-year-old neutered male Cairn Multifocally, mainly perivascularly, there are few terrier, (Canis familiaris).
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