A retrospective study comparing histopathological and immunopathological features of nasal planum dermatitis in 20 dogs with discoid lupus erythematosus or leishmaniosis

BACKGROUND

In areas endemic for leishmaniosis, discoid lupus erythematosus (DLE) and canine leishmaniosis (CanL) are the most common differential diagnoses for nasal planum erosive-ulcerative dermatitis in dogs.

HYPOTHESIS/OBJECTIVE

To compare histopathological and immunopathological features of canine nasal planum erosive-ulcerative dermatitis with depigmentation due to DLE or CanL.

ANIMALS

Nasal planum biopsies from dogs with nasal planum loss of architecture, depigmentation, swelling, erosions or ulcerations due to DLE (n = 14) or CanL (n = 6).

METHODS

Sections of paraffin-embedded samples, stained with haematoxylin and eosin were reviewed. Samples were examined using antibodies targeting T cells (CD3), B cells (CD20), macrophages (Mac387) and class II major histocompatibility complex (MHC II). Histopathological and immunophenotypical findings were compared between DLE and CanL cases.

RESULTS

Lichenoid and interface dermatitis were observed in both DLE and CanL cases. A nodular-to-diffuse, superficial and/or deep dermatitis with macrophages, lymphocytes and plasma cells was present only in CanL samples. CD20-positive cells predominated over CD3- and Mac387-positive cells in the two conditions. The percentage of dermal Mac387-positive cells was higher in CanL compared to DLE samples and the difference was statistically significant (P = 0.025).

CONCLUSIONS/CLINICAL IMPORTANCE

In this study, similar histopathological and immunopathological findings were observed in dogs with nasal planum lesions due to DLE or CanL. Therefore, in areas endemic for leishmaniosis, the presence of the parasite should be investigated in canine nasal planum dermatitis showing clinical and histopathological features suggestive of DLE.

Generalized Canine Discoid Lupus Erythematosus Responsive to Tetracycline and Niacinamide Therapy

Discoid lupus erythematosus (DLE) is a commonly reported canine autoimmune disease that normally presents with a phenotype consisting of erythema, depigmentation, scaling, erosions/ulcers, and scarring over the nasal planum and the proximal dorsal muzzle. Recently, two cases of a generalized variant of this disease have been reported, whose lesions responded to either systemic glucocorticoids or a combination of topical corticosteroids, topical tacrolimus, and the oral antimalarial hydroxychloroquine. The purpose of this report is to describe an 11 yr old shih tzu that presented with skin lesions consisting of multiple annular, erythematous papules and plaques, hyperpigmentation, adherent scaling, and atrophic scars over the caudal dorsum, flanks, craniodorsal thorax, and lateroproximal extremities. A diagnosis of generalized DLE was made based on the clinical presentation, histopathology, laboratory values, and direct immunofluorescence findings. Treatment consisted of oral tetracycline and oral niacinamide, which resulted in complete remission of clinical signs. This is the first documented report of generalized canine DLE responding to the described immunomodulating regimen. Such a combination might therefore be considered as a glucocorticoid and/or antimalarial alternative for the management of generalized DLE.

Successful treatment of a novel generalized variant of canine discoid lupus erythematosus with oral hydroxychloroquine

Discoid lupus erythematosus (DLE) is a common canine autoimmune disease that usually manifests as a localized ulcerative and scarring nasal dermatitis. We report herein a generalized variant of canine DLE successfully treated with the antimalarial immunomodulator hydroxychloroquine (HCQ). A 9-year-old hairless Chinese crested dog was presented with annular and polycyclic hyperpigmented and scaly skin lesions with central erosions, hypopigmentation and/or scarring on the trunk, neck and lateral extremities. Associated systemic signs were not seen. The clinical diagnosis of generalized DLE was supported by the demonstration of lymphocyte-rich interface dermatitis with epidermal atrophy and dermo-epidermal deposition of immunoglobulins and activated complement. As for human DLE, treatment was initiated with HCQ at 5 mg/kg once daily along with 2 weeks of 0.1% tacrolimus ointment and restriction of sun exposure. Over the following year, complete remission was maintained with HCQ at 5 mg/kg orally once daily with the exception of three relapses; two occurred during treatment induction and the third arose when the frequency of HCQ administration was reduced to every other day. Disease flares were controlled with 0.1% tacrolimus ointment alternating with 0.1% prednicarbate cream once daily for 5-10 days. Altogether, adverse drug events were not seen with this regimen. In summary, clinically, histologically and immunologically, this dog's disease mirrored the generalized discoid variant of chronic cutaneous lupus erythematosus of humans. The apparent benefit of HCQ, its safety and low cost warrant future investigations of its use for treatment of canine cutaneous lupus variants.