Canine and Feline Cutaneous Epitheliotropic Lymphoma and Cutaneous Lymphocytosis

Cutaneous lymphomas are divided into categories based on histologic evaluation of the skin and location of neoplastic lymphocytes. Epitheliotropic cutaneous lymphoma, also known as cutaneous T-cell lymphoma, is diagnosed when neoplastic lymphocytes show tropism for the epidermis and these cells infiltrate the epidermis and adnexae. In diagnosis of nonepitheliotropic cutaneous lymphoma, neoplastic lymphocytes are found mostly in the dermis and/or subcutis. Neoplastic cells are of either B-cell or T-cell origin. This article focuses on epitheliotropic cutaneous lymphomas and cutaneous lymphocytosis, which is considered a form of indolent lymphoma, in dogs and cats.