Pemphigus erythematosus and cutaneous epitheliotropic lymphoma in a Labrador Retriever dog

Background: Paraneoplastic pemphigus is an autoimmune blistering skin disease associated with concurrent neoplasia that is rarely observed in veterinary medicine. Case description: This case report presents a ten-year-old female Labrador Retriever dog with generalized seborrhea and alopecic, crusting and ulcerative lesions in the periocular and perioral regions, the lips and the groins. Findings/treatment and outcome: Hematology analysis showed a marked increase in the number of lymphocytes, while the rest of the values were normal. Skin biopsies were collected and the histological findings were consistent with pemphigus in association with an epitheliotropic lymphoma. Immunohistochemical analysis was performed. There was deposition of immunoglobulin G (IgG) in the basement membrane and in the intercellular space that corresponded with an immunostaining pattern characteristic of pemphigus erythematosus (PE). The lymphoma was positive to CD3 cells and was classified as a T-cell epitheliotropic lymphoma. Conclusion: To our knowledge, this is the first case of PE and cutaneous lymphoma coexisting in a dog, expanding the list of associations between immune-mediated diseases and cancer in dogs, and providing support to the eventual connection between autoimmunity and neoplasia in this species.