Immunopathology of vesicular cutaneous lupus erythematosus in the rough collie and Shetland sheepdog: a canine homologue of subacute cutaneous lupus erythematosus in humans

Cytotoxic dermatitis: Review of the interface dermatitis pattern in veterinary skin diseases

Interface dermatitis or lichenoid interface dermatitis refers to a cutaneous inflammatory pattern in which keratinocyte cell death is the essential feature. These terms have evolved from the originally described lichenoid tissue reaction. These lesions are the basis for an important group of skin diseases in animals and people where cytotoxic T-cell-mediated epidermal damage is a major pathomechanism. Yet, for largely historical reasons these commonly used morphological diagnostic terms do not reflect the essential nature of the lesion. An emphasis on subsidiary lesions, such as the presence of a lichenoid band, and definitions based on anatomical features, such as location at the dermo-epidermal location, may cause confusion and even misdiagnosis. This review covers historical aspects of the terminology, including the origin of terms such as "lichenoid." The types of cell death involved and the histopathologic lesions are described. Etiopathogenesis is discussed in terms of aberrations of immune/inflammatory mechanisms focusing on cutaneous lupus erythematosus, erythema multiforme, and Stevens-Johnson syndrome/toxic epidermal necrolysis. Mechanisms have most extensively been studied in humans and laboratory animals and the discussion is centered on these species. As interface dermatitis is firmly entrenched in dermatological parlance, rather than using "cytotoxic" as its substitute, the terminologies "interface cytotoxic dermatitis" and "panepidermal cytotoxic dermatitis" are recommended, based on location and extent of epithelium affected.

Cutaneous lupus erythematosus in dogs: a comprehensive review

Since the first description of discoid lupus erythematosus (LE) in two dogs in 1979, the spectrum of canine cutaneous lupus erythematosus (CLE) variants has expanded markedly.

In this review, we first propose an adaptation of the Gilliam-Sontheimer classification of CLE for dogs. We then review the signalment, clinical signs, laboratory and histopathology and treatment outcome of the currently recognized variants of canine CLE, which are vesicular CLE, exfoliative CLE, mucocutaneous LE and facial or generalized discoid LE. We end with a short description of the rare cutaneous manifestations of systemic LE in dogs.

Canine CLE variants are heterogeneous, some of them mirror their human counterparts while others appear—thus far—unique to the dog. As most CLE subtypes seem to have a good prognosis after diagnosis, veterinarians are encouraged to become familiar with the spectrum of often-characteristic and unique clinical signs that would permit an early diagnosis and the rapid implementation of an effective treatment.

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.

Mucocutaneous lupus erythematosus in dogs (21 cases)

BACKGROUND

The diagnosis of dogs with chronic juxtamucosal erosive lesions and histopathology typical of cutaneous lupus erythematosus (CLE) is unclear.

HYPOTHESIS/OBJECTIVES

We report herein 21 dogs with mucocutaneous erosive lesions and lupus-specific histopathology that we propose to be affected with mucocutaneous lupus erythematosus (MCLE), another variant of chronic CLE.

METHODS

Inclusion criteria were the presence of the following: (i) a >2 month history of chronic or recurrent skin lesions; (ii) erosions or ulcers predominating at mucosae or mucocutaneous junctions; (iii) microscopic lesions of CLE (i.e. a lymphocyte-rich interface dermatitis with basal keratinocyte damage); and (iv) a lack of complete remission following antimicrobials. Clinical questionnaires and skin biopsies were reviewed. Direct immunofluorescence and antinuclear antibody serology were performed whenever possible.

RESULTS

More than half of the 21 dogs were German shepherds or their crosses. The disease affected mostly dogs in their mid-adulthood and there was an over-representation of females. Erosions and ulcers predominated at genital/perigenital and anal/perianal areas, with a lower frequency of involvement of periocular, perioral and perinasal regions. In these dogs, there were no clinical signs suggestive of an associated systemic lupus erythematosus. Microscopic lesions were specific for CLE, but they were patchy and often infected with bacteria. The most common immunological finding was focal IgG deposition at the basement membrane zone. Lesions responded to varying interventions, but oral glucocorticoids led to a shorter time to complete remission. Relapses were common upon treatment tapering.

CONCLUSIONS AND CLINICAL IMPORTANCE

These observations support MCLE being another variant of canine CLE.

A case of vesicular cutaneous lupus erythematosus in a Border collie successfully treated with topical tacrolimus and nicotinamide-tetracycline

BACKGROUND

Canine vesicular cutaneous lupus erythematosus (VCLE) is an autoimmune skin disease of the Shetland sheepdog and rough collie, which manifests as an erosive dermatitis of sparsely haired skin of the ventrum and concave pinnae. Reported treatment consists of immunosuppression with glucocorticoids alone or in combination with azathioprine, but successful treatment is unpredictable.

OBJECTIVES

To report on the treatment of VCLE in a Border collie dog with topical 0.1% tacrolimus and nicotinamide in combination with tetracycline.

CASE REPORT

An 8-year-old male neutered Border collie was presented with multiple coalescing erosions on the ventral abdomen, groin and axillae and ulceration on the oral commissures. Clinical presentation, routine diagnostics, histology and immunohistochemistry were consistent with VCLE. Remission was achieved with topical 0.1% tacrolimus and combination therapy of nicotinamide and tetracycline.

CONCLUSION AND CLINICAL IMPORTANCE

This dog responded well to treatment with topical 0.1% tacrolimus, nicotinamide-tetracycline and sun avoidance. Complete remission was achieved after 2.5 months, and the dog was lesion free during a 1 year follow-up period.

Infiltrative lymphocytic mural folliculitis: A histopathological reaction pattern in skin-biopsy specimens from cats with allergic skin disease

This study was conducted to determine the prevalence of infiltrative lymphocytic mural folliculitis (ILMF) in skin-biopsy specimens from 354 cats with various inflammatory dermatoses and from 33 cats with normal skin. Although ILMF was present in 33/47 dermatoses evaluated, the prevalence of ILMF in allergic dermatoses (116/172 cats; 67%) was significantly greater than that in non-allergic dermatoses (61/182 cats; 33%). Cats with allergic dermatoses had a 4.1 times greater odds of having ILMF than cats with non-allergic dermatoses. ILMF was not observed in any of the normal skin specimens.

Cutaneous infiltrates and peripheral blood immune responses in dogs with immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis

This study characterizes T- and B-lymphocyte responses in the peripheral blood and lesional skin of dogs with immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis (ImR-LPP), a term previously proposed to denote a subpopulation of dogs with idiopathic pododermatitis. T-cell (CD3+, CD4+ and CD8+ ) and B-cell (CD21+) counts were significantly increased in both the epidermis and dermis of lesional ImR-LPP skin compared with that in pedal skin from healthy controls. CD3+ , CD4+, CD8+ and CD21+ cells were commonly observed in perivascular sites in the superficial dermis, periadnexally, beneath the dermal-epidermal (DE) junction and in the epidermis of lesional ImR-LPP skin. The CD8+ /CD3+ T-cell ratio in peripheral blood was significantly increased in the ImR-LPP group (0.42 versus 0.35 in controls). Serum IgA, IgG and IgM concentrations were all significantly elevated in affected dogs. Lymphocyte stimulation indices in ImR-LPP dogs were comparable with control levels except for a lower response to ionomycin (6.0 versus 11.1). Dogs with ImR-LPP had a higher incidence and mean (semi-quantitative) score for IgA, IgG and IgM deposits in the epidermis, and a significantly increased incidence of dermal IgA+, IgG+ and IgM+ mononuclear inflammatory cells. The results indicate that upregulated T- and B-lymphocyte responses may contribute to the pathogenesis of the skin lesions observed in dogs with ImR-LPP.

A study of dendritic cell and MHC class II expression in dogs with immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis

The term immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis (ImR-LPP) has previously been proposed to denote a sub-population of dogs with idiopathic pododermatitis. The objective of this study was to investigate dendritic cell (DC) and MHC class II antigen expression in lesional skin of dogs with ImR-LPP (n=47). Median epidermal CD1c(+) cell counts were 37.8 and 12.5 mm(-1) in ImR-LPP dogs and healthy controls (n=27), respectively (P<0.01), while the corresponding dermal cell counts were 180.9 and 45.0 mm(-2), respectively (P<0.01). Intra-epidermal clusters of DCs were observed in 18/47 dogs with ImR-LPP. Median epidermal MHC class II(+) cell counts were 32.5 and 10.5 mm(-1) in ImR-LPP dogs and healthy controls, respectively (P<0.01), while the corresponding dermal cell counts were 216.9 and 46.9 mm(-2), respectively (P<0.01). Dermal MHC class II(+) staining was primarily associated with DCs (47/47 dogs), mononuclear inflammatory cells (45/47), fibroblast-like cells (19/47) and vascular endothelium (14/47). The DC hyperplasia and increased MHC class II expression in lesional ImR-LPP skin are consistent with enhanced antigen presentation, and suggest that both parameters may contribute to the pathogenesis of ImR-LPP through the priming and activation of CD4(+) T cells. Equally, it is possible that the enhanced DC numbers observed in this study may contribute to the immunoregulation of steady-state pathology in lesional ImR-LPP skin through additional expanded, although as yet unresolved, mechanisms.

Uveodermatologic (VKH-like) syndrome in American Akita dogs is associated with an increased frequency of DQA1*00201

The Akita breed of dog is affected by a number of distinct immune-mediated diseases, including thyroiditis, sebaceous adenitis, pemphigus foliaceus, uveitis, polyarthritis, myasthenia gravis, and uveodermatologic (UV) syndrome. UV syndrome is manifested by progressive uveitis and depigmenting dermatitis that closely resembles the human Vogt - Koyanagi - Harada syndrome. This study examined the allelic diversity of the three DLA class II loci (DRB1, DQA1, and DQB1) in the American Akita dog, and the relationship of specific DLA class II alleles to the UV. Low allelic variation was demonstrated within genes of DLA class II. American Akita dogs possessed six of the reported 16 DQA1 alleles, but only eight of 61 reported alleles in DRB1 and nine of 47 reported alleles in DQB1. Almost one-half of American Akita dogs were homozygous for a single allele at DQA1 and up to a quarter at DRB1 and DQB1. DLA-DQA1*00201 was associated with a significantly higher relative risk (RR = 15.3) or odds ratio (OR = 15.99) for UV syndrome than other DLA class II alleles. No significant association was noted with haplotypes of DRB1, DQB1, and DQA1 alleles; DRB1*03201-DQA1*00201 trended toward significance. This study confirmed loss of DLA genetic diversity in the American Akita dog in common with other pure breeds of dog and suggested a role for certain DLA class II gene alleles in the pathogenesis of UV.