JPC SYSTEMIC PATHOLOGY

SPECIAL SENSES SYSTEM

April 2024

S-N03 (NP)

 

Signalment (JPC #1421244): Cat; age, gender and breed unspecified.

 

HISTORY: This cat had an abnormal pupillary opening, and the eye was surgically removed.

 

HISTOPATHOLOGIC DESCRIPTION: Eye: Expanding all parts of the anterior uvea, effacing the normal iris and expanding it up to 2mm thick and infiltrating predominantly the pars plana of the ciliary body, as well as the filtration angle, scleral plexus, and limbus is an unencapsulated, well demarcated, infiltrative, densely cellular neoplasm composed of sheets of neoplastic round cells separated by a fine, pre-existing fibrovascular stroma. The neoplastic cells have distinct borders, a scant amount of eosinophilic cytoplasm, and an irregularly round nucleus that is 1.5x the size of an erythrocyte, with clumped chromatin and one distinct nucleolus. Mitoses average 1 per 2.37mm². There is moderate anisokaryosis and anisocytosis. Neoplastic cells also infiltrate the ora ciliaris retinae, unilaterally into the choroid, and are present in low numbers within the anterior, posterior, and vitreous chambers. Throughout the iris, limbus, and spaces of Fontana, lymphatics are mildly to moderately dilated (edema). There is mild cupping of the optic nerve head.

 

MORPHOLOGIC DIAGNOSIS: Eye, uvea: Lymphoma, intermediate size, low grade, breed unspecified, feline.

 

GENERAL DISCUSSION:  

• Intraocular lymphoma is the most common metastatic neoplasm in both cats and dogs and is usually bilateral and presents as part of systemic disease; ocular involvement is especially prevalent in cats and typically occurs late in the course of the disease
  • E.g. Angioinvasive lymphoma, found primarily in the lungs with metastasis to the skin and eyes in a recent case report (Bacon et al. J Vet Diagn Invest, 2021)
• Lymphoma of the anterior uveal tract (iris, ciliary body) is most common presentation, but may also involve the choroid, retrobulbar tissue, conjunctiva, and eyelid
• Signs range from nodular iris infiltration to uveitis with hypopyon and hyphema
• Involvement of the choroid may result in retinal detachment, involvement of the trabecular meshwork and iridocorneal angle may result in secondary glaucoma 
• Involvement of the cornea is associated with advanced systemic disease and suggests poor prognosis
• Cats infected with FeLV or FIV have a higher incidence of lymphoma 
• Other forms of intraocular lymphoma:
  • Primary intraocular lymphoma is uncommon and is typically unilateral 

 

TYPICAL CLINICAL FINDINGS:

• Anterior uveitis is the most common presentation with thickening of uvea and lighter color to iris
• Exophthalmos if metastasis is in orbit and uveitis when ocular tissues are invaded
• Other clinical signs include—keratitis, vascularization, corneal edema, corneal hemorrhage, miosis, hypopyon, aqueous flare, secondary glaucoma, lens luxation, retinal hemorrhage, panuveitis, or a dense white circumcorneal band

 

TYPICAL GROSS FINDINGS: 

• Iridial color change and pallor from infiltrating neoplastic cells
• Dyscoria (abnormal pupillary shape or form)
• Uveal tract distorted by white to tan nodules
• Often bilateral and most commonly involves the anterior uvea (iris and ciliary body)

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Iris and ciliary body are most frequently infiltrated by neoplastic lymphocytes with scant cytoplasm
• Less frequently neoplastic cells extend into the choroid
• Occasionally there is a mixed population of neoplastic cells which may exhibit an epithelioid appearance

 

ADDITIONAL DIAGNOSTIC TESTS:

• Cytology: Aqueous humor aspirate with dogs presenting with anterior uveitis
• PARR 

                                                    

DIFFERENTIAL DIAGNOSIS:

• Anterior uveitis
• Malignant angioendotheliomatosis: Malignant intravascular lymphoma that arises from neoplastic lymphocytes of the vascular bed
• Selected other intraocular neoplasms:
  • Melanoma is the most frequent primary intraocular tumor in the cat, and melanocytic tumors are the most common intraocular tumors in all species
  • Iridociliary adenoma, adenocarcinoma 
  • Ocular sarcoma

 

COMPARATIVE PATHOLOGY:  

• Dogs: Diffuse infiltration of the anterior uvea is typical; distinct masses are uncommon
• Cattle: Retrobulbar lymphoma is common, is part of generalized lymphoma, and is the most frequent cause of exophthalmos; adult lymphosarcoma typically associated with BLV, disease is rare in BLV-free animals
• Horses: Systemic lymphoma is the most common neoplastic disease observed in the equine eye; infiltration of conjunctiva and eyelids (including third eyelid) are most common ocular manifestations
• Chickens: Marek’s disease (Gallid herpesvirus-2) causes iridial lymphoma

 

REFERENCES:   

1. Bacon R, Shivanna V, Gore M, Henningson J, Ganta C. Angioinvasive lymphoma (lymphomatoid granulomatosis) in a cat, with cutaneous and ocular metastasis. J Vet Diagn Invest. 2021;33(2):340-344. 
2. Cullen CL, Webb AA. Ocular manifestations of systemic disease. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2013:1949-1950, 2011, 2057, 2087.
3. Dubielzig RR. Tumors of the eye. In: Meuten DJ, ed. Tumors in Domestic Animals. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2017:912-914.
4. Gilger BC. Equine ophthalmology. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2013:1574-5.
5. Gould D, Papasoulitis K. Clinical microbiology and parasitology. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2013:308.
6. Grahn BH, Peiffer RL Jr. Veterinary ophthalmic pathology. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2013:512-514.
7. Hendrix DVH. Diseases and surgery of the canine anterior uvea. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2013:1183-1184.
8. Higgins D, Rose K, Spratt D. Monotremes and Marsupials. In:  Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London: Elsevier/Academic Press; 2018: 463-4. 
9. Ledbetter EC, Gilger BC. Diseases and surgery of the canine cornea and sclera. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2013:1033.
10. Narfström K, Petersen-Jones SM. Diseases of the canine ocular fundus. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2013:1376.
11. Ojkic D, Brash ML, Jackwood MW, Shivaprasad HL. Viral diseases. In: Boulianne M, ed. Avian Disease Manual. 7th ed. Jacksonville, FL: American Association of Avian Pathologists, Inc.; 2013:30-38.
12. Valli VEO, Kiupel M, Bienzle D. Hemopoietic system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:214-218; 222-226; 229-230.
13. Wilcock BP, Njaa BL. Special senses. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. St. Louis, MO: Elsevier; 2016:482.

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