Clinical response to isotretinoin and interferon-α of two dogs with cutaneous epitheliotropic T-cell lymphoma: a case report

Background: There is no specific therapy for cutaneous epitheliotropic T-cell lymphoma (CETL). The administration of retinoids in conjunction with interferon- (IFN-) in CETL has not been reported in dogs. Case presentation: Two dogs (Shih tzu and Miniature pinscher) presented with multiple nodular skin lesions. Histopathological examination revealed diffuse infiltrations of lymphocytes in the epidermis and dermis, with a CD3-positive immunophenotypic profile. Based on the clinical and histopathological examination, CETL was diagnosed. Both dogs were treated with isotretinoin in combination with IFN-alpha and showed clinical improvement with complete or partial remission. The disease in these dogs was well-controlled for more than 264 days of overall median survival time without any additional clinical signs after initiation of the treatment. In both the cases, the dogs were followed up for 27 months, and 10 months without any evidence of recurrence or metastasis, respectively. Conclusions: We describe the clinical efficacy of isotretinoin combined with IFN-alpha in 2 dogs with CETL. Long-term management with isotretinoin combined with IFN- was effective in treating CETL in these cases.