P-52 A case of juvenile cellulitis concurrent with hindlimb paresis in an English cocker spaniel puppy

Pemphigus vegetans is a very rare cutaneous autoimmune blistering acantholytic disease of humans that combines features of both pemphigus foliaceus and mucosal lesions of pemphigus vulgaris. We report here the clinical, histopathological and immunological findings in a dog whose lesions resembled those of pemphigus vegetans of humans. A 4-year old, greater Swiss mountain dog was presented with verrucous papules and crusts on the axillae and inguinal region. Within 3 months, lesions progressed to involve the thorax and ear pinnae, and then became generalized. Ulcers were observed in the oral cavity, anus and prepuce. Microscopic examination of mucosal and cutaneous biopsy specimens revealed a mixed pattern of deep intraepidermal neutrophilic and eosinophilic pustules with isolated and clustered acantholytic keratinocytes, along with suprabasal epidermal clefts leaving rounded basal keratinocytes at the bottom of the vesicles. These dual changes were also observed within the hair follicle epithelium. Dermal inflammation was mixed and perivascular. Direct immunofluorescence revealed IgG deposited around epidermal keratinocytes. Indirect immunofluorescence performed on normal canine gingival substrate uncovered antikeratinocyte IgG autoantibodies with a serum titre of 1:2500. Immunoblotting confirmed that circulating IgG autoantibodies recognized the extracellular segment of canine desmoglein-1 and human desmoglein-3. Treatment with azathioprine and oral glucocorticoids resulted in long-lasting complete remission. In this dog, clinical signs, microscopic skin lesions and immunological findings were deemed analogous to those of human Neumann-type pemphigus vegetans.
Funding: Self-funded.     

P‐50 Clinical,histological and immunological characteristics of Neumann‐type pemphigus vegetans in a dog

Pemphigus vegetans is a very rare cutaneous autoimmune blistering acantholytic disease of humans that combines features of both pemphigus foliaceus and mucosal lesions of pemphigus vulgaris. We report here the clinical, histopathological and immunological findings in a dog whose lesions resembled those of pemphigus vegetans of humans. A 4‐year old, greater Swiss mountain dog was presented with verrucous papules and crusts on the axillae and inguinal region. Within 3 months, lesions progressed to involve the thorax and ear pinnae, and then became generalized. Ulcers were observed in the oral cavity, anus and prepuce. Microscopic examination of mucosal and cutaneous biopsy specimens revealed a mixed pattern of deep intraepidermal neutrophilic and eosinophilic pustules with isolated and clustered acantholytic keratinocytes, along with suprabasal epidermal clefts leaving rounded basal keratinocytes at the bottom of the vesicles. These dual changes were also observed within the hair follicle epithelium. Dermal inflammation was mixed and perivascular. Direct immunofluorescence revealed IgG deposited around epidermal keratinocytes. Indirect immunofluorescence performed on normal canine gingival substrate uncovered antikeratinocyte IgG autoantibodies with a serum titre of 1:2500. Immunoblotting confirmed that circulating IgG autoantibodies recognized the extracellular segment of canine desmoglein‐1 and human desmoglein‐3. Treatment with azathioprine and oral glucocorticoids resulted in long‐lasting complete remission. In this dog, clinical signs, microscopic skin lesions and immunological findings were deemed analogous to those of human Neumann‐type pemphigus vegetans. Funding: Self‐funded.     

Altered immunohistochemical staining for desmoglein in skin biopsies in canine pemphigus foliaceus.

In this study, 50 cases of canine pemphigus foliaceus and 49 cases of canine superficial pyoderma were examined by immunohistochemical staining for patterns of desmoglein expression. In 31/50 (62%) of pemphigus foliaceus cases, there was an altered staining pattern for desmoglein consisting of distinct clumped deposits at the periphery of keratinocytes and/or dark cytoplasmic staining of acantholytic cells (consistent with internalization of desmoglein). In contrast, desmoglein staining in biopsies from cases of superficial pyoderma was diffusely pale without evidence for clumping or distinct internalization. This study demonstrates that epidermal desmoglein expression is altered in some cases of pemphigus foliaceus in dogs and suggests that immunohistochemical staining for this protein may be useful in diagnosis.     

Canine hyperplastic intraepidermal pustular and suprabasal acantholytic dermatosis with features of human pemphigus vegetans

Pemphigus vegetans is a rare autoimmune blistering acantholytic dermatosis of humans that combines unusually hyperplastic and verrucous pustular skin lesions and mucosal erosions. We report herein the clinical, histopathologic, and immunologic findings in a dog whose lesions resembled, but were not identical to, those of human pemphigus vegetans. A 4-year-old male Greater Swiss Mountain Dog presented with multifocal cutaneous verrucous and crusted papules and pustules, as well as skin and mucosal erosions and ulcers. Microscopic lesions consisted of exophytic papillated epidermal hyperplasia, superficial and deep intraepidermal acantholytic neutrophilic and eosinophilic pustules, and suprabasal epidermal clefts leaving rounded basal keratinocytes at the bottom of the vesicles. Direct and indirect immunofluorescence revealed antikeratinocyte IgG autoantibodies. Immunoprecipitation immunoblotting and immunoabsorption experiments with recombinant canine desmogleins confirmed that autoantibodies recognized desmoglein-1. In this dog, clinical and histopathologic features resembled those of human pemphigus vegetans, while circulating autoantibodies against canine desmoglein-1 were solely identified. This antigen target is different from that of the human disease in which antidesmoglein-3 autoantibodies are detected most commonly.     

Neutrophils contact to plasma membrane of keratinocytes including desmosomal structures in canine pemphigus foliaceus

Pemphigus foliaceus (PF) is an autoimmune blistering skin disease that affects certain mammals including dogs. In canine PF, neutrophils are infiltrated intensely into pustular lesions including acantholytic cells, although neutrophilic infiltration is not characterized in human PF. The roles of the neutrophils in the cutaneous lesions of canine PF have not yet been understood. The purpose of this study was to characterize the ultrastructural features underlying the acantholysis with pustule formation in canine PF. Four dogs diagnosed as PF on the basis of clinical signs, histopathological findings, and direct and indirect immunofluorescence examinations were performed. Electron microscopy revealed that the acantholytic cells were adjacent to multiple neutrophils in the pustules. At the contact points between neutrophils and acantholytic keratinocytes, half-desmosomes of acantholytic keratinocytes with intact attachment plaques were observed within invaginations of neutrophils. Furthermore, on the surface of acantholytic cells in the pustules, neutrophil granules seemed to be secreted to the surface of acantholytic cells and to degenerate the half-desmosome structures. Neutrophils were also observed within the epidermis adjacent to the pustule. At the intercellular gap between two dissociated keratinocytes, neutrophils inserted its pseudopodia into the gap between the two half-desmosomes of keratinocytes. These findings taken together suggested that, at least in the areas where we analyzed ultrastructurally, neutrophils contact desmosomal structures and seem to play some parts in separation of keratinocytes and degeneration of split-desmosomes in pustules of dogs with PF.     

Subepidermal linear alignment of mast cells in inflammatory dermatoses of the dog

A recent study demonstrated that 47.7% of dogs with Malassezia dermatitis had a subepidermal linear alignment of mast cells (SLAM). A retrospective histopathological study was conducted on 419 canine skin biopsies to determine if a SLAM was present in other inflammatory diseases. Cases examined included dogs with demodicosis, sarcoptic mange, dermatophytosis, pemphigus foliaceus, pemphigus erythematosus, discoid lupus erythematosus, systemic lupus erythematosus, erythema multiforme, dermatomyositis, staphylococcal pyoderma, primary seborrhea, arthropod bites, contact hypersensitivity, flea bite hypersensitivity, atopy, and food hypersensitivity. Three cases (3/419, 0.7%) were identified with SLAM. The diagnoses for these cases were atopy (1/23, 4%) with a secondary bacterial folliculitis (1/136, 0.7%), pemphigus erythematosus (1/18, 6%), and discoid lupus erythematosus (1/16, 6%). Based on this study, SLAM is significantly more common in Malassezia dermatitis than in other inflammatory diseases.     

A review of autoimmune skin diseases in domestic animals: I - superficial pemphigus

In humans, the pemphigus denomination encompasses a group of autoimmune blistering skin diseases with intraepidermal separation resulting from cell-cell detachment by acantholysis. Entities are classified based on the level of blistering in the epidermis, and both superficial (pemphigus foliaceus, IgA pemphigus) and deep (pemphigus vulgaris, pemphigus vegetans and paraneoplastic pemphigus) variants are recognized. In domestic animals, subsets of pemphigus have been recognized since the mid-1970s, and the disease classification resembles that used for human patients. This article reviews up-to-date knowledge on the epidemiology, clinical signs, histopathology, immunopathology and treatment outcome of superficial pemphigus in domestic animals. Detailed information on canine, feline, equine and caprine pemphigus foliaceus, canine and feline pemphigus erythematosus and canine panepidermal pustular pemphigus is provided.     

Development of an enzyme-linked immunosorbant assay (ELISA) for the serodiagnosis of canine dermatophytosis caused by Microsporum canis

Abstract In dogs, dermatophytosis should be considered in any case of alopecic, papular or pustular lesion. The aim of this study was to develop an enzyme-linked immunosorbant assay (ELISA) as an aid in the diagnosis of canine dermatophytosis. The antigen used was a whole fungal extract obtained from an isolate of Microsporum canis cultured on a liquid medium from the parasitized hair of a cat with patches of alopecia. To assess the ELISA performances, sera from 18 dogs with dermatophytosis caused by M. canis (group A, n = 18), 20 dogs with skin diseases other than dermatophytosis and 22 healthy dogs (group B, n = 42) were tested. Four further animals were tested: three with dermatophytosis caused by M. gypseum and one by T. mentagrophytes. A significant difference (P < 0.01, Wilcoxon's test, w = 364) was found between IgG-specific levels of sera of recently M. canis-infected dogs (infection < 15 days) and controls (although three dogs had negative titres at this stage). A highly significant difference (P < 0.001, w = 462) was noted between controls and dogs with infection of longer duration (> 30 days). All dogs had positive titres at this stage. A highly significant correlation (P < 0.001, Spearman's test, rho = 0.86) between duration of infection and IgG concentration was noted. The test has good sensitivity (83.3%) and high specificity (95.2%) but some dogs retained positive titres after elimination of infection. The sensitivity is higher than that of direct microscopic hair examination and similar to that of fungal culture with DTM (dermatophyte test medium).     

Ultrastructural localization of pemphigus vulgaris antigen on canine keratinocytes in vivo and in vitro

Pemphigus antigens were localized, by use fo immunoelectron microscopy, on canine keratinocytes in vivo on esophageal mucosa and in vitro on established cultured keratinocytes. Convalescent sera from a human being with pemphigus vulgaris and a human being with pemphigus foliaceus reacted with the interdesmosomal cytoplasmic keratinocyte membrane of canine esophagus. Cultured canine keratinocytes expressed the pemphigus vulgaris antigen in a similar pattern, but did not carry the pemphigus foliaceus antigen. The differential presence of cell surface antigens and its relation to various forms of the disease are discussed.     

IgG autoantibodies directed against desmoglein 3 cause dissociation of keratinocytes in canine pemphigus vulgaris and paraneoplastic pemphigus

Pemphigus is a group of autoimmune blistering diseases of the skin and mucous membranes. In human patients with pemphigus vulgaris (PV) and paraneoplastic pemphigus (PNP), IgG autoantibodies against desmoglein (Dsg) 3 and Dsg1 play pathogenic roles in blister formation. In contrast, the target for IgG autoantibodies that induce keratinocyte dissociation has not been elucidated in canine pemphigus. The aim of the present study was to determine whether anti-Dsg IgG autoantibodies are present and disrupt the cell-cell adhesion of keratinocytes in canine PV and PNP. The extracellular domains of canine Dsg3 were recognized by IgG in 3/5 (60%) canine PV sera tested. IgG against the extracellular domains of canine Dsg1 was detected exclusively in two dogs that had PV with the mucocutaneous phenotype. In addition, anti-Dsg3 IgG was identified in canine PNP serum. Furthermore, incubation of normal human keratinocytes (NHK) with mucocutaneous canine PV serum and canine PNP serum resulted in dissociation of the NHK sheets, whereas the removal of anti-Dsg3 IgG from these canine sera blocked this dissociation. The present study indicates for the first time that circulating anti-Dsg3 IgG antibodies capable of dissociating keratinocytes are present in dogs with PV and PNP.     

Severe dermatophytosis due to Trichophyton mentagrophytes var. interdigitale in flocks of green iguanas (Iguana iguana)

Objective : To describe the clinical, mycological, histopathological and molecular findings in green iguanas (Iguana iguana) affected with severe dermatophytosis in selected flocks near Tehran, Iran. Materials and Methods : Samples were collected from the scales of skin lesions and tested with standard mycological methods and dermatophyte‐specific PCR amplification analysis using the primer pair for the chitin synthase 1(CHS1) gene. Results : All iguanas were definitively diagnosed with dermatophytosis using both traditional and molecular diagnostic methods. PCR fingerprinting profiles using simple repetitive (GACA)4 primers showed that all diagnosed iguanas had the same pattern profile. Intraspecific variability was not observed for these isolates. Oligonucleotide sequencing of CHS1 gene PCR products confirmed Trichophyton mentagrophytes var. interdigitale as the infectious agent. Clinical Significance : These results suggest that (GACA)4‐based PCR has utility both as a simple and rapid method for identification of dermatophyte species and for differentiation of T. mentagrophytes variants.     

A canine pemphigus foliaceus case showing parallel relationship of disease activity and titer of serum anti-keratinocyte cell surface antibodies

A seven-year-old, spayed female mongrel dog was diagnosed as pemphigus foliaceus (PF) by clinical, histopathological and immunopathological observations. Serum antibodies against the cell surface of keratinocytes in the dog were detected by indirect immunofluorescence (IIF) using cryosectioned bovine esophagus as well as living cultured-canine keratinocytes as the substrates. When we compared the titers of IIF on bovine esophagus with its disease activity, the IIF titers reflected the disease activity throughout the time course. Our findings will suggest that sequential titration of serum antibodies by IIF will be useful for monitoring the serological disease activity in canine PF.     

Pemphigus foliaceus in 91 dogs

A retrospective study of 91 dogs with pemphigus foliaceus was performed. Clinical signs of the disease included crusts (n=79), pustules (n=36), and alopecia (n=33). Lesions were most common on the trunk (n=53), inner pinnae (n=46), face (n=37), and foot pads (n=32). Cytological evaluation revealed acantholytic keratinocytes in 37 of 48 dogs. Results of combination treatment with prednisolone and azathioprine were comparable to results with prednisolone therapy alone. More than half of the dogs achieved remission with appropriate therapy, and another 25% significantly improved.     

Safety and immunologic effects after inoculation of inactivated and combined live-inactivated dermatophytosis vaccines in cats

OBJECTIVE: To determine antidermatophyte immunologic effects of an experimental combined live-inactivated dermatophytosis vaccine (CLIDV) and a commercial inactivated dermatophytosis vaccine (IDV) in cats and to evaluate adverse effects associated with administration of these vaccines. ANIMALS: 20 healthy juvenile domestic shorthair cats. PROCEDURE: Cats were injected with 2 doses of CLIDV at the standard dosage or 1 dose of CLIDV at 10 times the standard dosage; IDV was administered at the manufacturer-recommended dosage. Cats were observed for illness and reactions at inoculation sites. Periodically, samples were obtained for fungal culture, lymphocyte blastogenesis test (LBT) as an indicator of cell-mediated immunity against dermatophyte antigens, and antidermatophyte IgG titers. Following vaccination, cats were challenge-exposed by topical application of Microsporum canis macroconidia and examined weekly for clinical signs of dermatophytosis. RESULTS: of 10 cats given CLIDV developed focal crusts at the injection site that resolved without treatment; these were areas of dermatophyte infection with the vaccine strain. Antidermatophyte IgG titers increased significantly with all vaccination protocols. Cellular immunity against M canis increased slightly and variably during the vaccination period and did not differ significantly between vaccinated and control cats. All cats developed dermatophyte infection after challenge exposure. Vaccination with CLIDV or IDV was associated with slightly reduced severity of initial infection. CONCLUSIONS AND CLINICAL RELEVANCE: Noculation with IDV or CLIDV did not provide prophylactic immunity against topical challenge exposure with M canis. Inoculation with either vaccine did not provide a more rapid cure of an established infection.     

Microbiological and histopathological features of canine acral lick dermatitis

The purpose of this study was to investigate microbiological and histopathological features of canine acral lick dermatitis (ALD). Microbial characteristics of ALD are poorly described in current literature. If infection is recognized, antimicrobial selection is usually empirical, based on appearance, cytology or surface culture, rather than deep tissue culture. It was hypothesized that cultures obtained from deep tissue would yield different results than predicted by surface culture and cytology, and that isolates from ALD have unpredictable susceptibility patterns showing resistance to antibiotics routinely administered for canine pyoderma. Biopsies were obtained from 31 lesions and submitted for aerobic, anaerobic and fungal culture, and histopathological evaluation. Surface aerobic culture and susceptibility and cytology were obtained for comparison in 22 dogs. Skin scrapings and dermatophyte culture were performed. Bacteria were isolated in 30 of 31 cases. Staphylococcus intermedius was isolated in 58% of deep cultures. Twenty per cent of deep isolates were methicillin-resistant Staphylococcus species. Forty-eight per cent of cases yielded organisms defined as multidrug resistant on deep culture. Only 57% and 55% of bacteria isolated from tissue culture were sensitive to amoxicillin-clavulanic acid and cefazolin, respectively. Cytology and superficial cultures did not correlate well with deep cultures. Surface culture predicted deep tissue isolates in eight of 22 cases. Microsporum gypseum was isolated from one dog. Histopathological features included acanthosis, follicular elongation, lymphoplasmacytic dermal inflammation, folliculitis, furunculosis, perihidradenitis, hidradenitis and vertical streaking fibrosis. Lesions associated with ALD warrant tissue bacterial cultures as the majority of cases yielded positive growth of bacteria differing from superficial culture and often resistant to empirical drugs.     

Dermatophytosis and papular eosinophilic/mastocytic dermatitis (urticaria pigmentosa-like dermatitis) in three Devon Rex cats

PRESENTING SIGNS: Three Devon Rex cats were presented with multiple erythematous papules, occasionally associated with crusting and hyperpigmentation, with a linear distribution on the head, neck, chest and abdomen. One cat also had multifocal alopecia with hyperpigmentation on the dorsum. DIAGNOSIS AND TREATMENT: Clinical and histopathological features were suggestive of papular eosinophilic/mastocytic dermatitis (urticaria pigmentosa-like dermatitis). In all cases, dermatophytosis was diagnosed: in cases 1 and 2 there was histopathological evidence of dermatophytosis, while fungal culture was positive for Microsporum canis in cases 2 and 3. In all cats, lesions disappeared following antifungal treatment. CLINICAL SIGNIFICANCE: Papular eosinophilic/mastocytic dermatitis in Devon Rex cats may represent either an atypical presentation of dermatophytosis or a clinical and histological reaction pattern to various diseases, including dermatophytosis and allergic diseases. Clinical differentiation is crucial as there are important implications regarding treatment and, in particular, the use of glucocorticoids, which are contraindicated in cases of dermatophytosis.     

Marked Acantholysis Associated with Dermatophytosis due to Trichophyton equinum in Two Horses

Resumen— Dos caballos adultos manifestaron un cuadro prurítico y de dolor asociado con una dermatitis generalizada de evolución rápida y consistente en la presencia de pápulas, pústulas y costras. El examen microscópico de extensiones citológicas a partir del exudado purulento reveló la presencia de numerosos queratinocitos acantoliticos, neutrófilos no degenerados y ausencia de microorganismos, lo que sugirió un diagnóstico de pénfigo foliáceo. Las biopsias de piel mostraron dermatofitosis, marcada acantolisis y creció Trichophyton equinum en cultivos fúngicos. Las lesiones en ambos animales se resolvieron tras administrar una terapia tópica con sulfuro de cal. Postulamos que los encimas proteoliticos liberados por las cepas de Trichophyton equinum aisladas fueron los responsables del alto grado de acantolisis detectada citológica e histológicamente. [Scott D. W. Marked acantholysis associated with dermatophytosis due to Trichophyton equinum in two horses (Acantolisis marcade en associación con dermatofitosis por Trichophyton equinum en dos caballos).
Abstract— Two adult horses developed a rapidly progressive, generalized, painful, pruritic, papular, pustular, and crusting dermatitis. Microscopic examination of direct smears made from purulent exudate revealed numerous acantholytic keratinocytes, nondegenerate neutrophils, and no microorganisms, suggesting a diagnosis of pemphigus foliaceus. Skin biopsies revealed dermatophytosis with prominent acantholysis, and fungal cultures were positive for Trichophyton equinum. The lesions in both horses resolved in association with topical applications of lime sulfur. It is hypothesized that proteolytic enzymes produced by the strains of T. equinum isolated were responsible for the prominent acantholysis seen cytologically and histologically.     

Review of 15 cases of pemphigus foliaceus in horses and a survey of the literature

The records of 15 horses with pemphigus foliaceus diagnosed on the basis of their history, clinical signs, histopathology and the exclusion of differential diagnoses were evaluated with respect to the age of onset, the clinical signs and the diagnostic tests used. There was no apparent breed predisposition. The horses' mean age was nine years, with a range from three months to 25.5 years, three were foals up to six months old and eight were nine years old or older. The most frequent lesions were scaling in 11, crusting in 10 and alopecia in 10, and they appeared most commonly on the face, neck and trunk, in 10 horses for each of these sites. The extremities were involved in nine of the horses, pruritus occurred in seven, and four of the horses had pustules. The clinical signs mostly corresponded with those described in previous reports, but signs of pain were not a prominent feature. Acantholytic cells were identified cytologically in four of six of the horses.     

A rapid molecular method for diagnosing epidemic dermatophytosis in a racehorse facility

Reasons for performing study: Identification of the species and strain of dermatophyte can play an effective role in control of disease outbreaks by establishing the source of infection. Current methods of identification are based on cultural and microscopic methods, often involving weeks before a positive identification are made. A rapid molecular diagnostic method would therefore be an important laboratory technique, but requires confirmation in equine clinical practice. Objectives: To test the sensitivity and specificity of molecular diagnostic methods applied to a racehorse herd from the Korean Racehorse Authority (KRA). Methods: A total of 57 DNA samples were collected from hairs and crusts of skin lesions in KRA racehorses with histories and clinical signs suggestive of dermatophytosis, which was confirmed by dermatophyte‐specific PCR amplification analysis using the primer pair for the chitin synthase 1 (CHS1) gene. Results: Thirty‐eight racehorses were definitively diagnosed with dermatophytosis using molecular and traditional diagnostic methods. PCR fingerprinting profiles using simple repetitive (GACA)₄ primers showed that all diagnosed horses had the same pattern profile. Oligonucleotide sequencing of CHS1 gene PCR products confirmed Trichophyton mentagrophytes as the infectious agent. Conclusions: This study demonstrates that the PCR‐based molecular diagnostic method is sensitive and specific and offers fast precise diagnosis of dermatophytosis in horses.     

Dermatophyte granulomas caused by Trichophyton mentagrophytes in a dog

Multiple, dermal and subcutaneous nodules developed in a young female Manchester Terrier dog that had a chronic history of superficial dermatophytosis. Skin biopsy specimens of the nodules revealed granulomatous inflammation in the deep dermis and subcutis with branching fungal organisms. Cultures of multiple biopsy specimens from the nodules all yielded Trichophyton mentagrophytes. The lesions in this dog were similar to granulomatous dermatophytosis, a skin disease that has been reported in Persian cats and one Yorkshire Terrier dog.