JPC SYSTEMIC PATHOLOGY
SPECIAL SENSES
May 2018
S-N02 (NP)

Signalmnent (AFIP 2149189):  German shepherd dog  

HISTORY:  This German shepherd military working dog was euthanized following diagnosis of multicentric lymphoma.  At necropsy, the cornea of the left eye was opaque.

HISTOPATHOLOGIC DESCRIPTION:  Slide 2A:  Eye:  Arising from the iris, expanding and effacing the remaining iris and ciliary body, infiltrating and partially blocking the filtration angle, and infiltrating the cornea and sclera is a large, multinodular, poorly demarcated neoplasm that fills and expands the anterior compartment.  Neoplastic cells are arranged in short streams and bundles on a fine fibrovascular stroma and are characterized by:  variably distinct cell borders, a moderate amount of eosinophilic cytoplasm that contains abundant dark brown granular pigment (melanin) that often obscures the nucleus, round to oval nuclei with finely stippled chromatin and often a single, prominent nucleolus.  The mitotic rate is 0-1 per 10 HPF 40x fields.  Multifocally there are variably sized areas of coagulative necrosis admixed with free melanin granules.  Scattered throughout and surrounding the neoplasm are numerous melanomacrophages, occasional lymphocytes and plasma cells, and rare single cell necrosis.  Multifocally dissecting the neoplasm and adhered to the posterior capsule of the lens is a broad band of collagen admixed with fibrin, melanocytes and melanophages (cyclitic membrane).  Diffusely the retina is absent and the remaining underlying retinal pigment epithelium is hypertrophied (“tombstoning”). 

MORPHOLOGIC DIAGNOSIS:  Eye, uvea: Melanocytoma, German shepherd dog, canine.

Signalment (AFIP 2348405):  Tissue from a cat

HISTORY:  There is a white to pale yellow-colored nodule involving the ciliary body and iris.

HISTOPATHOLOGIC DESCRIPTION:  Slide 2B:  Eye:  Diffusely expanding the iris and ciliary body up to 2.5 mm, infiltrating the adjacent sclera, and blocking the filtration angle is an unencapsulated, poorly demarcated, polygonal to spindle cell neoplasm.  Neoplastic cells are arranged in nests and packets and, rarely, form short streams that encompass multiple small caliber dilated vessels and are separated by a scant fibrovascular matrix.  Neoplastic cells have variably distinct cell borders and a moderate amount of finely granular eosinophilic cytoplasm.  Occasionally the cytoplasm contains a brown granular pigment (melanin).  Nuclei are round to oval with finely stippled chromatin and a single prominent nucleolus.  Mitoses average 1-2/HPF.  Scattered throughout the neoplasm are melanomacrophages and multifocal single cell necrosis.   Multifocally within the posterior chamber there is a moderate amount of fibrin.

Slide 2C:  Warthin-Starry 3.2:  Many of the neoplastic cells contain variable amounts of intracytoplasmic, silver-positive (agyrophilic), granular material (melanin).

MORPHOLOGIC DIAGNOSIS:  Eye, iris: Melanoma, diffuse, breed not specified, feline.

ETIOLOGIC DIAGNOSIS:  Ocular melanoma

GENERAL DISCUSSION: 

PATHOGENESIS: 

TYPICAL CLINICAL FINDINGS: 

Dogs:

Cats:

Horses:

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

Dogs:

Cats:

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY: 

REFERENCES: 

  1. Beckwith-Cohen B, Teixeira LBC, Dubielzig RR. Presumed primary intraocular chondrosarcoma in cats.  J. Vet. Diag. Invest. 2014; 26(5):  664-668.
  2. Dubielzig RR, Ketring KL, McLellan GJ, Albert DM. Veterinary Ocular Pathology: A Comparative Review. New York: Saunders Elsevier; 2010;162-165,184-187, 282-290.
  3. Labelle P. The Eye. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St Louis, MO: Elsevier; 2017; 1302-1304.
  4. 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 Saunders; 2016; 482-485.


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