Veterinary Medicine - June 2008 - (Page 319)

cats is unknown. In both of the reported cases of conjunctival lymphoma and in the cat presented here, the FeLV test results were negative. Two of the three cats survived long-term (> 1 year),9 while the remaining one was lost to follow-up.8 FIV infection increases the incidence of lymphoma but is thought to play an indirect role in its tumorigenesis.13 Immunophenotyping Immunophenotyping is being performed in cases of lymphoma in many species to provide prognostic information,6,15 and these tumors have been classi ed according to cytochemical and immunologic markers.14 Immunophenotyping is more readily available for lymphoid tumors in dogs than in cats, and it is generally considered to be less useful as a prognostic indicator in cats.6,16 Lymphoid tumors arise from T and B lymphocytes17 and from natural killer cells.14,17 As in this case, feline lymphoma is most often the B-cell type.15,18 A B 8. Horizontal ultrasonograms of the right orbit six weeks after exenteration. A vascularized mass is present within the orbit (between the two stars), which was thought to be a return of the tumor. B is the same view as A; the arrow points to the area of blood ﬂow demonstrated by color ﬂow Doppler ultrasound. Treatment Treatment protocols for feline lymphoma are determined after disease staging. Staging involves performing a CBC, a serum chemistry pro le, a urinalysis, FeLV and FIV testing, a lymph node or organ biopsy, bone marrow aspiration, and thoracic and abdominal radiography.13,20 Additional tests might include thoracic and abdominal ultrasonography and computed tomography. Chemotherapy is the treatment of choice for most forms of systemic lymphoma. Effective chemotherapeutic agents include cyclophosphamide, vincristine sulfate, and prednisolone. Cytosine arabinoside and lomustine have also been used with some success.13,20 Lymphoma cells are radiation-sensitive, and radiation therapy, which was recommended in this case, can be an effective treatment for the localized forms of lymphoma. REFERENCES 1. Cockerham GC, Jakobiec FA. Lymphoproliferative disorders of the ocular adnexa. Int Ophthalmol Clin 1997;37(4):39-59. 2. Hardy JWD. Hematopoietic tumors of cats. J Am Anim Hosp Assoc 1981;17:921-940. 3. Valli, VEO. The hematopoietic system. In: Jubb KVF, Kennedy PC, Palmer N, eds. Pathology of domestic animals. Vol 3. 4th ed. San Diego, Calif.: Academic Press, 1993;101-265. 4. Mahony OM, Moore AS, Cotter SM, et al. Alimentary lymphoma in cats: 28 cases (1988-1993). J Am Vet Med Assoc 1995;207(12):1593-1598. 5. Gabor LJ, Malik R, Can eld PJ. Clinical and anatomical features of lymphosarcoma in 118 cats. Aust Vet J 1998;76(11):725-732. 6. Twomey LN, Alleman AR. Cytodiagnosis of feline lymphoma. Compend Contin Educ Pract Vet 2005;27:17-31. 7. Gilger BC, McLaughlin SA, Whitley RD, et al. Orbital neoplasms in cats: 21 cases (1974-1990). J Am Vet Med Assoc 1992;201(7):1083-1086. 8. Radi ZA, Miller DL, Hines ME. B-cell conjunctival lymphoma in a cat. Vet Ophthalmol 2004;7(6):413-415. 9. Holt E, Goldschmidt MH, Skorupski K. Extranodal conjunctival Hodgkin’s-like lymphoma in a cat. Vet Ophthalmol 2006;9(3):141-144. 10. Shields CL, Shields JA, Carvalho C, et al. Conjunctival lymphoid tumors: clinical analysis of 117 cases and relationship to systemic lymphoma. Ophthalmology 2001;108(5):979984. 11. Rebhun WC, Del Piero F. Ocular lesions in horses with lymphosarcoma: 21 cases (1977-1997). J Am Vet Med Assoc 1998;212(6):852-854. 12. Day, MJ, Kyaw-Tanner M, Silkstone MA, et al. T-cell-rich B-cell lymphoma in the cat. J Comp Pathol 1999;120(2):155-167. 13. Ettinger SN. Principles of treatment for feline lymphoma. Clin Tech Small Anim Pract 2003;18(2):98-102. 14. Vail DM, Moore AS, Ogilvie GK, et al. Feline lymphoma (145 cases): proliferation indices, cluster of differentiation 3 immunoreactivity, and their association with prognosis in 90 cats. J Vet Intern Med 1998;12(5):349-354. 15. Gabor LJ, Can eld PJ, Malik R. Immunophenotypic and histological characterisation of 109 cases of feline lymphosarcoma. Aust Vet J 1999;77(7):436-441. 16. Fan TM. Lymphoma updates. Vet Clin North Am Small Anim Pract 2003;33(3):455-471. 17. Rojko JL, Kociba GJ, Abkowitz JL, et al. Feline lymphomas: immunological and cytochemical characterization. Cancer Res 1989;49(2):345-351. 18. Wellman ML, Hammer AS, DiBartola SP, et al. Lymphoma involving large granular lymphocytes in cats: 11 cases (19821991). J Am Vet Med Assoc 1992;201(8):1265-1269. 19. Walton RM, Hendrick MJ. Feline Hodgkin’s-like lymphoma: 20 cases (1992-1999). Vet Pathol 2001;38(5):504-511. 20. Mooney SC, Hayes AA, MacEwen EG, et al. Treatment and prognostic factors in lymphoma in cats: 103 cases (19771981). J Am Vet Med Assoc 1989;194(5):696-702. Non-Hodgkin vs. Hodgkin-like lymphoma Another possible prognostic indictor is the classi cation of the initial tumor as either non-Hodgkin or Hodgkin-like lymphoma.1 In cats, both Hodgkin-like9 and non-Hodgkin lymphomas have been reported in the conjunctiva, but to our knowledge, only one report of each disease has been published.9,12 The tumor in the cat reported here appears to be most similar to conjunctival B-cell lymphoma (non-Hodgkin lymphoma)8 because it consisted primarily of B cells and lacked Reed-Sternberg cells.19 Non-Hodgkin lymphoma arises from monoclonal expansion of either T or B lymphocytes, and in people, most are B cell in origin.1 In people, a diagnosis of Hodgkin lymphoma generally carries a better prognosis for long-term survival than does a diagnosis of non-Hodgkin lymphoma.1 This better prognosis appears to be the same in cats19; however, there are so few known cases of conjunctival lymphoma in cats that such a conclusion cannot be made. EXTRAS See for information on anesthesia in cats undergoing ophthalmic surgery. VETERINARY MEDICINE June 2008 319

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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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