Cutaneous epitheliotropic T-cell lymphoma in the cat: a review of the literature and five new cases.

Cutaneous epitheliotropic T-cell lymphoma (CETL) is characterized by cutaneous infiltration of neoplastic T lymphocytes with a specific tropism for the epidermis and adnexal epithelium. This disease is reported very rarely in the cat. Clinical data were collected from an informal discussion with veterinary dermatologists through the Vetdermlist (vetderm@lists.ncsu.edu). In parallel, case archives of two European diagnostic histopathology laboratories (Institut de Pathologie et Génétique/Bio.be Gosselies, Belgium and the School of Veterinary Sciences, University of Bristol, UK) were reviewed. Fifteen cases with a good clinical description were selected, and five sets of skin biopsies were available for review. Cutaneous epitheliotropic T-cell lymphoma generally affects older cats with no apparent sex or breed predisposition. Solitary or multiple lesions were reported without predilection for any particular location. The lesions consisted of erythematous plaques or patches, scaly alopecic patches and nonhealing ulcers or nodules, which sometimes mimicked an eosinophilic plaque. Pruritus was rarely reported. No lesions affecting the oral mucosa were observed. Clinical diagnosis of CETL is more challenging in cats than in dogs. Final diagnosis must be based on histopathological examination of skin biopsy samples. The characteristic lesions of feline CETL are similar to those reported in the dog, but involvement of the adnexal glands was not observed in this series (n=5). The neoplastic T cells were generally small to medium in size. The survival time of cats with CETL seems to be more variable than that of affected dogs. Too few cases have been evaluated to permit clear recommendations to be made with respect to treatment.