Archive Case #238: Canine Discoid Lupus Erythematosus

Clinical Clues

1. A dog is brought in for slowly progressive changes to the nose but remains otherwise well.
2. The nasal planum loses pigment and its usual cobblestone surface, then develops crusts and shallow erosions.
3. The lesions sometimes worsen after bright sunlight, yet the haired muzzle and most other skin are spared.
4. Surface cytology and skin sampling find no convincing bacterial, fungal or mite cause.
5. A nasal-planum biopsy shows lymphocyte-rich interface dermatitis with basal-cell injury, without the pustules and acantholytic cells expected for pemphigus foliaceus.
6. Taken with the distribution and exclusion of mimics, the findings support canine facial discoid lupus erythematosus.

Diagnosis

Canine Discoid Lupus Erythematosus

Nasal-planum-predominant depigmentation, loss of cobblestoning and lymphocytic interface injury support canine discoid lupus erythematosus after common mimics are checked. Sun sensitivity alone cannot establish it. Pemphigus foliaceus usually has pustular acantholysis; infection or solar dermatitis needs separate exclusion rather than being dismissed from appearance alone. Remember: A pale crusted canine nose is a pattern, not a diagnosis; combine distribution and biopsy with checks for infection and other immune disease.

Educational Use

Vetdle archive cases are educational veterinary games for diagnostic reasoning practice. They do not provide veterinary advice, diagnosis, treatment, or professional medical guidance.