Veterinary Medicine - June 2008 - (Page 318)

A challenging case PEER-REVIEWED not changed in size or shape since the last examination. Thus, the owner elected to continue to monitor the cat’s health rather than pursue radiation therapy. A year and a half after the exenteration, the cat continues to do well. The cause of the lymphoma remains unknown. It is also unknown whether the previous blindness of unknown pathogenesis in the eye and the onset of the neoplasm are associated. DISCUSSION Lymphomas, the most common tumors in domestic cats,2 are solid tumors composed of neoplastic cells of lymphocytic lineage.1 Lymphoma is often more dif cult to diagnose in cats than in dogs because in dogs, multicentric distribution and generalized lymphadenopathy are common, while lymphoma in cats usually involves internal structures such as the alimentary tract,3-5 thymus,3 and mediastinum.6 Solitary lymph node involvement has been reported in cats as well, and most commonly involves lymph nodes of the head and face.5 In cats, ocular lymphomas have been reported in the anterior uvea,5 orbit,7 and conjunctiva.8,9 Conjunctival lymphomas are relatively rare, extranodal neoplasms that have been reported in people,10 horses,11 and cats.8,9 They probably arise from the mucosa-associated lymphoid tissue present in the conjunctiva, which would be consistent with the B-cell immunophenotype of this cat’s lymphoma. Conjunctival lymphoma has the best prognosis of any ocular adnexal lymphomas. In a retrospective study, only 36 of 117 (31%) patients with conjunctival lymphoid in ltration already had or eventually developed systemic lymphoma.10 The study suggested that the tumor’s location when the disease was rst identi ed was prognostic for the development of systemic lymphoma and that patients with tumors initially arising from extra-limbal sites (e.g. fornix or midbulbar) were less likely to develop systemic lymphoma.10 However, too few reported cases of this tumor exist to determine whether tumor location is a prognostic indicator in cats. Immunocompromised pets and people In people, conjunctival lymphoma occurs with increased frequency in immunode cient individuals and may be associated with viral infections or may be familial.1 Lymphoma in cats is often associated with viremia or latent FeLV infection12; however, as testing for FeLV infection and vaccinations have increased, the incidence of FeLVpositive lymphoma has decreased.13 In the alimentary and mediastinal forms of feline lymphoma, FeLV infection worsens the prognosis for long-term survival and response to chemotherapy.14 However, the association between FeLV infection and conjunctival lymphoma in 318 June 2008 VETERINARY MEDICINE face.In

Table of Contents Feed for the Digital Edition of Veterinary Medicine - June 2008

Veterinary Medicine - June 2008 Contents Leading Off Clinical Exposures Idea Exchange A Challenging Case: Conjunctival Lymphoma in a Cat Updates on Canine Hypoadrenocorticism Product Preview CE Form Advertiser Index Marketplace/Classifieds Mind Over Miller Clinical Edge - June 2008 Table of Contents Managing Diabetes Mellitus in Cats: What Makes it Work? Porcine Insulin Zinc Suspension in the Management of Feline Diabetes Mellitus Monitoring Diabetes Mellitus in Diabetic Cats Feline Diabetes Mellitus: Important Client Communication Points

Veterinary Medicine - June 2008

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