Case 180525-2

Five-year-old, male, castrated mixed-breed dog (presumed German shepherd cross)

This dog was rescued in 2014 when he was approximately a year old. He was previously diagnosed with cardiac arrhythmia and dropped pulses. Since his rescue, he was intermittently alopecic and had scaly, erythematous skin lesions on the face, paw pads, and along the dorsum. The hair grew back white. His right eye was enucleated due to uveitis and glaucoma in 2016. The patient was suspected to have either Vogt-Koyanagi-Harada syndrome or systemic lupus erythematosus (SLE) based on a biopsy sample collecgted approximately one year prior to this current submission.

Upon physical examination, there was multifocal alopecia and hyperpigmentation of the dorsum. Multifocal crusts and erythema was present in the interdigital spaces of all four paws, with fissuring of the tarsal pad of the right pelvic limb. The skin of the left hock and left elbow had multifocal crusts. Multifocal crusting, erythema and alopecia were present on the face, including both pinnae. Punch biopsies were taken from the tarsal foot pad, the dorsal neck, and the face.

This slide has a bisected punch biopsy of haired skin from the face, including epidermis, dermis, and extending to the deep dermis. A thick lichenoid band of mostly histiocytes, with smaller numbers of neutrophils, lymphocytes and plasma cells, is immediately subjacent to the epidermis and extends to the perifollicular dermis. Small, dark brown melanin granules are in the cytoplasm of some histiocytes. A thick crust of cellular keratin and serum with karyorrhectic debris overlies some sections. Occasionally these crusts contain coccoid bacteria.

N/A

Haired skin : Severe, diffuse, lichenoid predominantly histiocytic dermatitis with admixed lymphocytes, plasma cells and neutrophils, serous crusts, multifocal parakeratosis, and fine intrahistiocytic pigment granules.<?p>

Haired skin: Multifocal subepidermal clefting.

TThe lichenoid band of mostly histiocytes with finely granular melanin in their cytoplasm is suggestive of uveodermatologic syndrome. The extent of the clinical lesions however are rather unusual for Vogt-Koyanagi-Harada -like syndrome. The dermo-epidermal separation is considered a secondary change due to the heavy inflammation abutting the basement membrane zone. It would be very atypical to see a predominance of histiocytes with cutaneous lupus. More over there is no overt evidence of keratinocyte cytotoxicity (interface dermatitis) as is typically seen with lupus erythematosus. There is no evidence of pemphigus foliaceus in the sections examined.

A type IV hypersensitivity to melanin has been demonstrated in humans with this condition, and it is suspected that a similar process occurs in the dog. The syndrome is slightly different in humans, however, as the disease is associated with deafness and neurologic signs, which have not been reported in dogs. In dogs, uveitis precedes or occurs concurrently with the skin disease. Manifestation of skin disease may be mild or may not occur at all, and the uveitis is the more clinically significant aspect of the disease, as it may lead to glaucoma and loss of sight. Skin lesions typically occur on the face , footpads, and perineum and include depigmentation, erythema, scaling and variable pruritis. There is a breed predisposition for Akitas, Chow Chows, Siberian huskies, Alaskan malamutes, and their cross-breeds.

We thank Dr. Verena Affolter for contributing this case.