Canine Cutaneous Epitheliotropic T-Cell Lymphoma

s European Veterinary Conference Voorjaarsdagen 2008 | 91 Dermatology Cellular phenotype The classic neoplastic cells in canine CETL are CD3+ (a common marker of all T-lymphocytes) and in 80% of the cases CD4-/CD8+ cytotoxic T cells. In 20% of the cases, CD4-/CD8lymphocytes (natural killer cells) are found. In man, 90% of CETL cases are due to clonal expansion of T-helper lymphocytes (CD4+/CD8-). Gene rearrangement analysisBecause clonal proliferation in humans typically occursfrom a single lymphocyte, the population of neoplasticlymphocytes contains the same signature generearrangement. In contrast, reactive lymphocytes containa mixture of gene rearrangements. This can be detectedusing DNA analysis from a skin biopsy to confirm thediagnosis of neoplasia in borderline cases. It can be alsoused to monitor the response of T cell lymphoma totreatment by reduction of clonality. DNA can be extractedfrom fresh, frozen or formalin-fixed tissue. The techniqueshowed a very good sensitivity (91%) and specificity(95%) in 77 dogs with lymphoid neoplasia.The prognosis for dogs with canine CETL is poor. Themean survival time after diagnosis is a few months to 2years. Euthanasia is often requested by the ownersbecause of the severe skin condition.Many treatment protocols for CETL have been reported,the large number attesting to the fact that none of themhave good efficacy. Currently the most promisingprotocols include the use of Lomustine or CCNU. In dogs,the recommended dosage is 60 to 70 mg/m2 orally every3 weeks with a mean of 4 treatments. Recentlyretrospective studies of dogs with CETL cases showed anoverall response rate of 78 to 83%. However, survivaltimes were not listed. Although the disease cannot becured, treatment frequently increases the quality of life. References1. Day MJ. Immunophenotypic characterizationof cutaneous lymphoidneoplasia in the dog and cat. J.Comp.Path.1995, 112,79-96.2. De Lorimier L. P., Updates on the management of canineepitheliotropic cutaneous T-cell lymphoma. Vet Clin Small Anim2006, 36: 213-28. 3. Fournel-fleury C, Ponce F, Felman P, Blavier A, Bonnefont C, Chabanne L, Marchal T, Cadore Jl, Goy-thollot I, Ledieu D, Ghernati I, Magnol JP. Canine T-cell lymphomas: a morphological, immunological, and clinical study of 46 new cases. Vet Pathol. 2002