There is increasing recognition of clinical variants of lupus erythematosus. However, the diagnosis for dogs with chronic erosive juxtamucosal lesions with histopathology consistent with cutaneous lupus erythematosus (CLE) is unclear. This retrospective study described 21 such cases of mucocutaneous lesions in dogs proposed to have mucocutaneous lupus erythematosus (MCLE).
All dogs had chronic lesions of >2 months duration predominating at mucosae or mucocutaneous junctions. The lesions were incompletely responsive to appropriate antibiotic and antiseptic treatment and had histopathology consistent with CLE. Lesions commonly developed in the genital/perigenital area and perianal area with a lower frequency of involvement on perioral, periocular, and nasal skin. Most dogs had involvement of 2 or more regions. The earliest clinical signs were usually mucocutaneous erosion/ulceration, dyschezia, and/or dysuria. Mucocutaneous lesions were typically symmetrical and consisted of well-demarcated areas of erosion and ulceration, erythema, hyperpigmentation, and crusting without concurrent signs of systemic disease. Histological lesions consisted of lymphocyte-rich interface dermatitis with evidence of basal keratinocyte damage; evidence of bacterial infection was common.
Dogs responded well to varying treatment protocols (eg, glucocorticoids, niacinamide, tetracycline/doxycycline). Complete remission was achieved in 16/17 dogs, although some remained on low drug doses long-term. Treatment with oral glucocorticoids often led to shorter treatment times; relapses were common during drug tapering. This disease, distinct from discoid lupus erythematosus, is believed to be a variant of chronic CLE.