P-35 Nonlethal junctional epidermolysis bullosa in a dog

Junctional epidermolysis bullosa (JEB) is a rare hereditary or autoimmune bullous skin disease of humans, horses and dogs. It has been reported that JEB patients have blisters, erosions or ulcers affecting the face, digits and tail predominantly. Histopathologically, separation of the epidermis and dermis occurs within the lamina lucida of the basement membrane zone (BMZ) and, biochemically, there is a deficiency of laminin 5, integrin α6β4, or BPAG2. Mutations in the alpha-chain of laminin 5 in nonlethal JEB in dogs has been reported. Our patient was an 8-month-old female mixed-breed dog that presented with hair loss, blisters and scar formation on the face, trunk and feet that were present since 2 months of age. Histopathology of the skin revealed atrophy of the hair follicles and liquefactive degeneration of the dermo-epidermal junction with minimal cell infiltration. Electron microscopy revealed that blister formation was located within the lamina lucida. These findings corresponded with canine JEB. The immunofluorescence test (IIF) revealed that the expression of BMZ proteins, including laminin 5, BPAG2, integrin α6β4 and type XVII collagen, were not decreased compared with normal skin. The IIF using the patient's serum showed a negative reaction. Although the disease has progressed, the patient is still alive one year after the onset of lesions. Moreover, although we could not determine the genetic background or the causative proteins, this is likely a case of hereditary JEB because of the young age at onset and autoantibodies against the BMZ were not detected. Funding: Self-funded.