Retinoblastoma

From Dog

Retinoblastoma are a rare autosomal-recessive neuroepithelial tumor of the canine retina[1].

Invasion of the anterior segment by retinoblastoma is a well recognized if not very common complication, and in that it may simulate ocular inflammation it is a significant source of misdiagnosis[2].

Rarer diffuse infiltrating growth patterns have been reported where the retina may appear clinically normal despite tumor growth infiltration of the anterior chamber, including the iris[3].

Affected dogs usually present with visual deficits and presence of blood in the anterior chamber.

Ophthalmoscopy usually reveals the presence of a hemorrhagic mass in the posterior chamber[4].

Imaging studies, particularly CT and MRI may be required to determine metastatic involvement of the central nervous system.

Diagnosis is based on histological examination of enucleated material, with characteristic Flexner-Wintersteiner rosettes. These tumors show strong immunoreactivity with S-antigen and glial fibrillary acidic protein[5].

A differential diagnosis would include glaucoma, acquired adenoma and adenocarcinoma of the mature ciliary epithelium[6], ocular toxocariasis[7] and hemangiosarcoma.

Topical corticosteroid ointments and systemic prednisolone may temporarily alleviate edema associated with this tumor, but enucleation is usually recommended.

References

  1. Yuzbasiyan-Gurkan V et al (1993) Linkage studies of the esterase D and retinoblastoma genes to canine copper toxicosis: a model for Wilson disease. Genomics 15(1):86-90
  2. Zimmerman LE (1985) Retinoblastoma and retinocytoma. In: Spencer W, ed. Ophthalmic pathology: an atlas and textbook. 3rd ed. Philadelphia: Saunders. pp:1292-1351
  3. Nicholson DH & Norton EW (1980) Diffuse infiltrating retinoblastoma. Trans Am Ophthalmol Soc 78:265-289
  4. Antal M & Németh B (1976) Tubular structures in the endothelia of the retina and in retinoblastoma. Klin Monbl Augenheilkd 169(4):496-499
  5. Syed NA et al (1997) Retinoblastoma in a dog. Arch Ophthalmol 115(6):758-763
  6. Schäffer EH (1992) Pathology of the retina. Tierarztl Prax 20(5):510-518
  7. Verallo O et al (2012) Diagnostic aspects and retinal imaging in ocular toxocariasis: a case report from Italy. Case Report Med 2012:984512