15-year-old castrated male domestic medium hair cat, Felis cats This cat had a 4-week history of hyphema and corneal opacity of the right eye (OD). Physical examination revealed dyscoria, epiphora, conjunctival hyperemia, 2+ buphthalmos, 2+ aqueous flare, hemorrhage within the anterior chamber, corneal midstromal neovascularization and edema, and increased intraocular pressure (54 mmHg) OD. The eye was enucleated and submitted for microscopic examination.
The slides submitted to the conference contain the vertical section of a feline globe, which was collapsed as the result of a reported posterior rupture during enucleation.Â The globe is characterized by diffuse infiltration of the choroid and anterior uvea by a neoplastic population of epithelial cells causing extensive retinal detachment and complete occlusion of the filtration angles.Â The neoplastic cells are cuboidal to tall columnar and arranged in tubules, commonly containing either pale basophilic wispy material (mucin) or amorphous cell debris.Â Cells have indistinct cell borders and moderate to ample amount of eosinophilic cytoplasm, frequently with apical projections that stain basophilic with hematoxylin & eosin and magenta (i.e.Â positive) with the Periodic-Acid Schiff (PAS) reaction, consistent with mucus.Â The nuclei are round to oval and finely stippled with one or two prominent nucleoli.Â Anisocytosis and anisokaryosis are moderate.Â Twelve mitoses are counted in ten high power fields.Â Neoplastic cells focally infiltrate the deep corneal stroma anterior to the Descemet's membrane and extensively colonize the posterior aspect of the Descemets membrane, as well as the iris, ciliary body and inner retina.Â Additionally, aggregates of neoplastic cells extend through the sclera into the episcleral stroma, with evidence of vascular invasion and, in the dependent portion, focal scleral thinning (staphyloma) and prominent regionally extensive periscleral desmoplastic spindle cell proliferation.Â Moderate numbers of lymphocytes and plasma cells are multifocally present within the uveal tract amongst the neoplastic population.Â The detached retina exhibits diffuse atrophy of the nerve fiber and ganglion cell layer, as well as multifocal edema.Â There is mild cupping of the optic nerve head with mild gliosis (not present in all sections).Â Mild midstromal neovascularization is present in the peripheral cornea.Â The lens (not present in the submitted sections) exhibits extensive subcortical cataractous change, characterized by eosinophilic spherical globules (Morgagnian globules) and migration of the epithelium along the posterior lens capsule.Â Within sections of eyelid (not submitted), moderate numbers of lymphocytes and plasma cells infiltrate the subepithelial stroma.Â Blood vessels are moderately congested, accompanied by mild acute edema.
Eye: Metastatic carcinoma, with secondary glaucoma, retinal detachment and atrophy, multifocal uveitis, and cataractous change
Three-view radiographs of the thorax revealed a soft tissue opacity in the left caudal lung lobe dorsally, the medial aspect of which appears to be associated with the left caudal lobar bronchus.Â Abdominal ultrasound did not reveal any abnormalities.
Carcinoma metastatic to the eye
The pattern of neoplastic cell infiltration in this case is typical of intraocular metastatic carcinoma.(1,2) With the exception of multicentric lymphoma, carcinomas are the neoplasms most frequently reported to metastasize to the globe in cats.(1) The majority of intraocular metastases involve the posterior uvea likely because of the rich blood supply to this tissue.(1,2) Ophthalmoscopic findings in cats with angioinvasive pulmonary carcinoma typically include wedge-shaped areas of chorioretinal degeneration most prominent in the tapetal fundus radiating away from the optic disc.Â Vascular attenuation with areas of lumen occlusion, serous exudation, and retinal hemorrhage in the peripapillary retina are also common.Â The pathogenesis of the ophthalmoscopic lesions is thought to be neoplastic embolization of branches of the short posterior ciliary arteries, which supply retinal and choroidal circulation.(1) Histopathological examination of affected globes shows neoplastic cells within ocular blood vessel lumens and widespread retinal and tapetal necrosis.Â Growth of the metastatic lesions along the vascular endothelium leads to segmental loss of perfusion and subsequent necrosis of the overlying retina and choroid.(1,2)
Carcinomas reported as metastasizing to the feline eye have been of pulmonary, sweat gland, mammary, uterine, and squamous cell origin.(1,2) In this case, the metastatic carcinoma in the eye was presumed to be of pulmonary origin based on the radiographic findings of a tissue opacity in the caudal lung, the most commonly affected lung field by primary lung tumors in cats.(4) CT scan and fine needle aspirate of this lung lesion with follow-up with the oncology team was recommended.Â The owners declined any further workup, however.Â The cat was euthanized three months later, at which point it was emaciated and unresponsive.Â No necropsy was performed.
Primary lung tumors are uncommon in cats, with older animals more commonly affected (mean age 12 years).(3,4) Lesions tend to be malignant and with a grave prognosis.Â When diagnosed early, with no evidence of metastatic disease, solitary lung tumors may be surgically resected.Â The degree of differentiation of the pulmonary neoplasm has been suggested to be a prognostic indicator, with cats with moderately differentiated primary lung tumors having reportedly a significantly longer survival time (median 698 days) than cats with poorly differentiated primary lung tumors (median 75 days).(5) However, early diagnosis is difficult since most cats initially present with nonspecific clinical signs or signs related to metastases.3 Lameness, associated with metastasis to the bone and skin of the digits,(3) or visual deficits (associated with intraocular metastasis),(1) may be the only initial presenting sign.Â Intraocular metastasis may be underestimated since ophthalmoscopic and microscopic examinations are not performed on a routine basis in many cases.Â Other sites of metastasis of primary lung tumors in cats include skeletal muscle, and multiple thoracic and abdominal organs.(4) Thorough clinical examination and thoracic radiography can provide a high index of suspicion of the primary neoplasm.(4) Cytologic evaluation of cells obtained by fine-needle aspiration of the lung mass, as well as of cells collected from thoracic fluid or bronchoalveolar lavage can help determine the diagnosis.(3,4) Effective treatment has yet to be demonstrated for metastatic lung carcinomas in cats.Â As a result, most cats with metastatic lung carcinoma die or are euthanized within 6 weeks of diagnosis.(5)
Eye: Metastatic carcinoma.
This is a excellent descriptive slide with extensive ocular changes.Â Conference participants agreed the neoplasm is likely the result of metastasis from the pulmonary mass identified clinically.Â In the cat, lymphoma is by far the most prevalent metastatic tumor in the eye, although virtually any malignant neoplasm can localize within the uveal tract.(6)
Primary uveal neoplasms are common in dogs and cats and considerably more common than metastatic tumors, with the exception being metastatic uveal lymphoma in cats.Â Among primary ocular tumors, melanoma, lymphoma, posttraumatic sarcoma and iridociliary adenocarcinoma are most common in cats.Â Iridociliary adenocarcinoma is a reasonable differential in this case, but these typically benign neoplasms tend to infiltrate and expand the posterior chamber, often in solid sheets, in contrast to this case which filed along the uvea and choroid forming tubules.(6) Additionally, a PAS-positive basement membrane is highly conserved in these neoplasms and can aid in distinguishing from metastatic disease.(7) Extraocular metastasis from these primary tumors is rare or nonexistent; however, secondary complications are often significant, with glaucoma or intractable hyphema occurring most commonly.(6)
Of greater significance in cats are posttraumatic sarcomas, which are usually high-grade neoplasms of lens epithelial origin following lens rupture.(6) The majority of these are of the spindle cell variant and are often not recognized for years following a traumatic event.Â They are highly invasive within the globe though rarely metastasize.Â A round cell variant resembling lymphoma and osteo- or chondrosarcoma also occur following lens trauma, albeit at a much lower frequency.(2)
1. Cassotis NJ, Dubielzig RR, Gilger BC, Davidson MG.Â Angioinvasive pulmonary carcinoma with posterior segment metastasis in four cats.Â Vet Ophthalmol.Â 1999;2(2):125131.
2. Dubielzig RR, Ketring KL, McLellan GJ, Albert DM.Â Metastatic neoplasia.Â In: Veterinary ocular pathology: A comparative review.Â New York: Saunders Elsevier.Â 2010; 97-103,309-315.
3. Goldfinch N, Argyle DJ.Â Feline lung-digit syndrome: unusual metastatic patterns of primary lung tumours in cats.Â J Feline Med Surg.Â 2012;14(3):202-8.
4. Hahn KA, McEntee MF.Â Primary lung tumors in cats: 86 cases (1979-1994).Â J Am Vet Med Assoc.Â 1997;211(10):1257-60.
5. Hahn KA, McEntee MF.Â Prognosis factors for survival in cats after removal of a primary lung tumor: 21 cases (1979-1994).Â Vet Surg.Â 1998;27(4):307-11.
6. Njaa BL, Wilcock BP.Â The ear and eye.Â In: Zachary JF, McGavin MD, eds.Â Pathologic Basis of Veterinary Disease.Â 5th ed.Â St.Â Louis, MO: Elsevier Saunders; 2012:1228-1230.
7. Wilcock B, Dubielzig RR, Render JA.Â Histological classification of ocular and otic tumors of domestic animals.Â Second series.Â Vol IX.Â Washington, D.C.: Armed Forces Institute of Pathology; 2002:26.