Thymoma-associated exfoliative dermatitis in a rabbit

A 5-year-old rabbit with generalized scaling is presented. Multiple skin scrapings and acetate tape impressions were negative for mites and Malassezia. Culture for dermatophytes was also negative. Skin biopsies showed similarities with sebaceous adenitis described in rabbits (absence of sebaceous glands, perifollicular lymphocytic infiltrate at the level of the absent sebaceous glands, lymphocytic mural folliculitis, interface dermatitis). The owners refused any treatment and 2 months later the rabbit was euthanized due to anorexia. At necropsy a mass was found in the anterior mediastinum. Histopathology confirmed a diagnosis of thymoma. A possible paraneoplastic skin disease was suspected, based on similarities with thymoma-associated exfoliative dermatitis in cats.     

Symmetrical alopecia, scaling and hepatitis in a rabbit

A 5-year-old rabbit with inappetence, symmetrical alopecia and skin lesions was examined. No mites or Malassezia were found in skin scrapings and tape impressions and dermatophyte culture was negative. Trial therapy with ivermectin did not reduce skin lesion severity, and euthanasia was performed because of anorexia after 1 month. Histopathology of the skin showed hyperkeratosis, lymphocytic exocytosis, cell-poor interface dermatitis (lymphocytic infiltration and apoptotic cells in basal layer of epidermis), absence of sebaceous glands and lymphocytic mural folliculitis comparable to sebaceous adenitis and thymoma-associated exfoliative dermatitis previously described in rabbits. The liver exhibited an interface hepatitis, comparable to autoimmune hepatitis in man. The occurrence of morphological similarities to exfoliative dermatitis and sebaceous adenitis in rabbits, in association with an autoimmune hepatitis, has not been described before.     

Successful treatment of sebaceous adenitis in a rabbit with ciclosporin and triglycerides

A 4-year-old rabbit was presented with a chronic exfoliative dermatitis and patchy alopecia. General physical examination revealed no abnormalities. Skin scrapings and fungal culture were negative. A blood sample was obtained for a complete blood cell count and biochemical profile, and yielded results that were within normal limits. Radiographic examination of the thorax excluded the presence of a thymoma. Histopathology of the skin showed orthokeratotic hyperkeratosis, absence of sebaceous glands and mural lymphocytic folliculitis, consistent with sebaceous adenitis. Oral treatment was started with ciclosporin dissolved in a medium-chain triglyceride solution (Miglyol 812), combined with essential fatty acids and topical propylene glycol sprays. Within 2 months of treatment, complete regression of skin lesions and regrowth of hair was observed. Serum chemistry values including kidney and liver function tests remained within reference range during the course of treatment. Histopathological examination of control biopsies of the skin showed presence of normal sebaceous glands and active hair follicles. Treatment was changed to a different pharmaceutical formulation of ciclosporin without Miglyol and deterioration of clinical signs was noticed. Using pure Miglyol 812, however, resulted in a gradual improvement of 60%. A nearly complete response was again observed after re-administration of the combination ciclosporin/Miglyol. It is hypothesized that sebaceous adenitis in the rabbit is most likely due to an autoimmune reaction directed at the sebaceous glands and a defect in lipid metabolism. The outcome indicates that a combination of ciclosporin and Miglyol 812 is a promising new treatment for sebaceous adenitis in rabbits.     

Abnormal sebaceous gland differentiation in 10 kittens ('sebaceous gland dysplasia') associated with generalized hypotrichosis and scaling

A rare congenital dermatosis, characterized by progressive hypotrichosis with variable scaling and crusting, occurred in 10 short-haired kittens in North America and Europe. Lesions appeared at between 4 and 12 weeks of age, commencing on the head and becoming generalized. The tail was spared in two kittens. Generalized scaling was mild to moderate, often with prominent follicular casts. Periocular, perioral, pinnal and ear canal crusting was occasionally severe. The skin was thick and wrinkled in two kittens. Histologically, the main lesion was abnormal sebaceous gland morphology. Instead of regular differentiation from basal cells to mature sebocytes, the glands were composed of a haphazard collection of undifferentiated basaloid cells, some partly vacuolated and a few containing eosinophilic globules. Mitotic figures and apoptotic cells were present in an irregularly thickened follicular isthmus. Lymphocytic mural folliculitis and mild sebaceous adenitis were rare. Orthokeratotic hyperkeratosis and follicular casts were present. Hair follicles were of normal density and were mostly in anagen, but some contained malacic hair shafts. Perforating folliculitis, leading to dermal trichogranuloma formation, occurred occasionally. Further biopsy samples taken at 2 years and at 3 and 4 years, respectively, from two kittens revealed similar but often more severe sebaceous gland lesions. Hair follicles were smaller, with many in telogen. The young age of onset suggests a genetic defect interfering with sebaceous and, possibly, follicular development. These lesions are discussed with reference to studies of mouse mutants in which genetic defects in sebaceous differentiation cause a similar phenotype of hyperkeratosis and progressive alopecia.     

Sebaceous adenitis in the Akita: clinical observations, histopathology and heredity

Ninety-seven pure-bred Akitas were examined clinically and histologically for sebaceous adenitis. The diagnosis was established histologically in 23 Akitas by demonstrating an inflammatory reaction targeted against the sebaceous glands or a reduction in the number of glands. The clinical course of sebaceous adenitis in the Akita was similar to that seen in other breeds. The first skin lesions occurred mainly on the dorsal midline and ears. Compared with the Poodle, the age at first onset of the disease was more variable and the hair loss affected mainly the undercoat. The progression of sebaceous gland destruction varied between dogs and was not seen in all cases. Because bud-like sebaceous gland proliferation could be identified, it seems that regeneration of the sebaceous glands may occur. An autosomal recessive inheritance appears to be possible. Apart from a genetic background, immune-mediated factors possibly influence the onset and course of sebaceous adenitis.     

Effects of cyclosporine A on clinical and histologic abnormalities in dogs with sebaceous adenitis

OBJECTIVE: To evaluate the effects of cyclosporine A in the treatment of sebaceous adenitis in dogs. DESIGN: Open-label clinical trial. ANIMALS: 12 dogs with sebaceous adenitis. PROCEDURE: Dogs were treated with cyclosporine A at a dosage of 5 mg/kg/d (2.3 mg/lb/d), PO, for 12 months and reevaluated every 4 months. A clinical score was calculated by grading the extent of alopecia and severity of follicular casts as absent, mild, moderate, or severe in each of 17 body regions. Biopsy specimens were obtained and examined histologically and by means of immunohistochemical staining. RESULTS: Mean clinical score was significantly decreased, compared with baseline score, after 4 months of treatment and remained low after 8 and 12 months. Histologically, the severity of inflammation was significantly decreased, as were numbers of macrophages, CD3+ T cells, and major histocompatibility complex class II-expressing cells. The percentage of hair follicles with sebaceous glands increased, suggesting regeneration of sebaceous glands. Clinical signs recurred when cyclosporine administration was discontinued. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of cyclosporine A at a dosage of 5 mg/kg/d may reduce the inflammation associated with sebaceous adenitis in dogs. Long-term treatment appears to be neccessary to control the disease.     

Alopecia in a black Labrador retriever associated with focal sub‐follicular panniculitis and sebaceous adenitis

A 6‐year‐old entire male black Labrador retriever was presented with nonpruritic multicentric, well‐demarcated alopecia of 12‐weeks duration. Skin biopsies from the margins of alopecic regions showed sebaceous adenitis and sub‐follicular panniculitis. Biopsies from alopecic areas showed severe follicular atrophy with residual fibrous tracts, loss of sebaceous glands and lymphohistiocytic panniculitis beneath individual atrophic hair follicle groups. These features differed from previous reports of pilosebaceous diseases of dogs and appeared to extend the spectrum of inflammatory patterns in presumed immune‐mediated adnexal diseases of this species. During the 12‐month follow‐up, there was partial hair regrowth without treatment but alopecia was permanent in the centre of larger lesions.     

Degenerative mucinotic mural folliculitis in cats

A novel form of mural folliculitis is described in seven cats. Clinically, all cats exhibited generalized alopecia with scaling or crusting that was more pronounced over the head, neck, and shoulders. The face and muzzle of all cats was unusually thickened. Six of seven cats were progressively lethargic but did not demonstrate any other consistent systemic abnormalities. Histologically, there was severe mixed inflammation of the wall of the follicular isthmus in all cats, accompanied by some follicular destruction in five cats. Sebaceous glands were not affected. All cats had variable, but often striking, follicular mucin deposition, as well as epidermal hyperkeratosis and crusting. The cause of the severe mural folliculitis was not identified, and all cats responded poorly to immunomodulating therapy. Follicular mucinosis may be a nonspecific finding, likely reflective of the follicular lymphocytic milieu, and does not always herald follicular lymphoma.     

Sebaceous adenitis in Havanese dogs: a retrospective study of the clinical presentation and incidence

Sebaceous adenitis is a suspected immune-mediated disease that targets and destroys sebaceous glands. This retrospective study evaluated the clinical presentation and incidence of sebaceous adenitis in Havanese dogs. Sebaceous adenitis was diagnosed in 35% (12 of 34) of Havanese dogs presented over a 5-year period. Onset of clinical signs occurred during young adulthood. Follicular casts were present in 92% (11 of 12) of affected dogs. Other common clinical signs included alopecia and hypotrichosis. The trunk, head and ears were commonly affected, with 67% (8 of 12) of cases having pinnal and/or external ear canal involvement. Secondary pyoderma was seen in 42% (5 of 12) of dogs. Histopathology revealed absent sebaceous glands in 83% (10 of 12) and a lymphoplasmacytic periadnexal infiltrate in 92% (11 of 12) of samples. Treatment included multiple modalities. Cyclosporin was prescribed in 83% (10 of 12) of cases. Other systemic therapies included vitamin A and fatty acid supplementation. Topical therapies included antiseborrhoeic shampoos and sprays, and oil soaks. Follow-up ranging from 2 months to 3 years was obtained in 67% (8 of 12) of dogs. Improvement ranged from minimal to marked, with better clinical response associated with longer duration of treatment. Owners with follow-up of more than 1 year commonly reported occasional flares of the clinical signs. This study found that sebaceous adenitis was a common diagnosis in Havanese dogs, that the ears were commonly affected and that a lymphoplasmacytic periadnexal infiltrate associated with absent sebaceous glands was frequently seen on dermatohistopathological examination.     

Three cases of immune-mediated adnexal skin disease treated with cyclosporin

Cyclosporin is currently considered a new and interesting drug in veterinary dermatology for the treatment of immune-mediated skin diseases, and a safe and effective alternative to immunosuppressive therapy with glucocorticoids. The authors report a case of granulomatous folliculitis and furunculosis and of sebaceous adenitis in two cats and a case of alopecia areata in a dog, successfully controlled with cyclosporin.     

Successful Treatment of Idiopathic Sebaceous Adenitis in a Lionhead Rabbit

A 15-month-old, ovariohysterectomized female Lionhead rabbit was presented with generalized chronic exfoliative dermatitis and patchy alopecia. General physical examination revealed no abnormalities apart from a body condition score of 4 of 9. Ectoparasitic infestation, dermatophytosis, Malassezia dermatitis, epitheliotropic lymphoma, thymoma-associated exfoliative dermatitis, and autoimmune hepatitis-associated exfoliative dermatitis were excluded on the basis of skin scrapings, fungal culture, cutaneous histopathology, thoracic radiography, and the results of hematologic and biochemical analyses. Histopathology of the skin showed orthokeratotic hyperkeratosis, absence of sebaceous glands and mural lymphocytic folliculitis, consistent with sebaceous adenitis. The extent and severity of the skin lesions were scored by the Rabbit Dermatitis Extent and Severity Index adapted from the recently published Canine Atopic Dermatitis Extent and Severity Index–03. Once-daily oral treatment with 5 mg/kg of ciclosporin A dissolved in an equal amount of a medium-chain triglyceride solution (Miglyol 812; Bufa, Uitgeest, The Netherlands) was initiated, but the response to this was poor. Therefore, while maintaining the oral treatment, topical treatment with phytosphingosine products was given. The rabbit's coat was clipped and a phytosphingosine 0.2% microemulsion spray (daily), a phytosphingosine 0.1% shampoo (weekly), and a phytosphingosine 1% spot-on treatment (weekly) were applied. Nine months later, there had been significant hair regrowth on previously hairless areas and the Rabbit Dermatitis Extent and Severity Index confirmed the marked improvement with a 91% reduction in the original score. Serum ciclosporin concentrations were undetectable throughout the treatment period.     

Morphologic and immunologic characterization of a canine isthmus mural folliculitis resembling pseudopelade of humans

The clinical, histopathologic and immunopathologic features of a novel form of isthmus mural folliculitis in dogs, which resembles pseudopelade in humans, were characterized. Clinically, dogs exhibited variably distributed foci of alopecia that persisted without treatment or did not respond to immunosuppressive therapy. Histopathologically, mixed mononuclear cell infiltrates, largely lymphocytes, infiltrated the follicular isthmus. Occasionally, inflammation extended above and below the follicular isthmus but did not involve the hair bulb or the epidermis. Severe follicular atrophy and variable atrophy of sebaceous glands occurred in all dogs. Folliculotropic lymphocytes exhibited most commonly CD3 and CD8 (cytotoxic T cells). Autoantibodies specific for the lower hair follicle were detected in the serum of affected patients. Western immunoblotting demonstrated binding of these antibodies to multiple follicular keratinocyte proteins, including hair keratins and trichohyalin. Lack of hair regrowth (in contrast to canine alopecia areata), as well as location of inflammation and extreme atrophy of adnexal units are similar to findings seen in human pseudopelade.     

Cyclosporine-responsive granulomatous sebaceous adenitis in a dog

Granulomatous sebaceous adenitis was diagnosed in a 2 year old spayed Miniature Pinscher. Initial treatment with isotretinoin for 3 weeks resulted in little response and decreased tear production. Immunosuppressive doses of prednisone for 3 weeks resulted in mild response of the dermatitis; however, the dog developed transient diabetes mellitus secondary to this treatment. Cyclosporine (5 mg/kg of body weight, po, q 12 h) resulted in good clinical response for 12 months, but histologically, the sebaceous glands remained absent. Although cyclosporine has immunosuppressive properties, this drug also has inhibitory effects of keratinocyte proliferation. These mechanisms may explain the beneficial response of cyclosporine in the treatment of granulomatous sebaceous adenitis in this dog.     

An evaluation of the clinical, cytological, infectious and histopathological features of feline acne

Clinical, cytological, microbial and histopathological features of feline acne were investigated in 22 cats referred or volunteered to a veterinary dermatology practice in the south-west region of the USA. For comparison, same parameters were evaluated in five unaffected pet cats. Additionally, all cats were evaluated by immunohistochemistry (IHC) for the presence of feline calicivirus (FCV) and feline herpes virus (FHV-1) in acne lesions. The age of onset of acne in affected cats ranged from 6 months to 14 years with a median of 4 years. The most common dermatologic lesions were comedones (73%), alopecia (68%), crusts (55%), papules (45%) and erythema (41%). Pruritus was reported in 35% of the affected cats. Cytological evidence of Malassezia pachydermatitis was present on 4/22 (18%) of affected cats. Microsporum canis was isolated from a single affected cat. Bacteria were isolated from 10 of the 22 (45%) affected cats; coagulase-positive staphylococci and alpha-haemolytic streptococci were most common. Histopathological features included lymphoplasmacytic periductal inflammation (86%), sebaceous gland duct dilatation (73%), follicular keratosis with plugging and dilatation (59%), epitrichial gland occlusion and dilatation (32%), folliculitis (27%), pyogranulomatous sebaceous adenitis (23%) and furunculosis (23%). In one affected cat from a household with five cats, simultaneously having feline acne, FCV antigen was detected in the biopsy of the chin by IHC. Chin tissue samples from all other affected cats, as well as the five healthy cats, were negative by IHC for FCV and FHV-1 antigens.     

Histopathological differences between canine idiopathic sebaceous adenitis and canine leishmaniosis with sebaceous adenitis

Sebaceous adenitis (SA) may be idiopathic (ISA) or associated with other disorders. The purpose of the present study was to compare the cutaneous histopathology of SA in cases in which Leishmania organisms were detected by immunohistochemistry (IHC) with that of cases diagnosed as ISA. Skin sections of 29 patients were evaluated histologically and divided into two groups, one characterized by several epidermal and subepidermal lesions, a granulomatous to pyogranulomatous nodular to diffuse dermatitis involving the sebaceous glands and a positive IHC for Leishmania spp. The other group was characterized by orthokeratotic hyperkeratosis, follicular keratosis with different degrees of pyogranulomatous to granulomatous SA, lack of nodular dermatitis and a negative IHC for Leishmania spp. Hidradenitis was present in both groups. From these results it can be concluded that SA in canine Leishmaniosis (CL) is usually present together with a nodular to diffuse dermal infiltrate and epidermal and subepidermal lesions, and that SA in the absence of dermal inflammation is probably not associated with or suggestive of CL, even in regions where the disease is endemic.     

A multicentre placebo‐controlled clinical trial on the efficacy of oral ciclosporin A in the treatment of canine idiopathic sebaceous adenitis in comparison with conventional topical treatment

Canine idiopathic sebaceous adenitis (ISA) is an inflammatory reaction of sebaceous glands, potentially resulting in their complete loss. It is considered a T‐cell‐mediated disease, but its precise pathogenesis is still unknown. Topical treatment with oil soaks, humectants and shampoos is effective but laborious. Ciclosporin A (CsA), an immunomodulatory drug, has recently been shown to ameliorate the clinical picture of ISA and to reduce inflammation greatly. It is, however, an expensive treatment option. The objective of this multicentre, partly double‐blinded, randomized controlled study was to evaluate the efficacy of ciclosporin A, either alone or with topical therapy, in comparison to conventional topical treatment alone, as measured by the primary end‐points alopecia and scaling, and multiple histopathological secondary objectives. Thirty‐four dogs with an established diagnosis were treated for 4–6 months and were evaluated before, during and after therapy. Both CsA and topical therapy demonstrated efficacy in this study. Differences between the treatment protocols were marginal. Topical treatment, both alone and in combination with CsA, appeared to reduce scaling more effectively than CsA alone. Both therapies reduced alopecia. There is evidence of a synergistic benefit on both scaling and alopecia, if both treatment options are combined. Inflammation of the sebaceous glands is also best reduced by a combination of both CsA and topical therapy. There is evidence that regeneration of sebaceous glands is best achieved by CsA, either given alone or in combination with topical treatment.     

Severe bilaterally symmetrical alopecia in a horse

A 9-year-old Tennessee Walking Horse gelding was presented for diagnosis of the cause of extensive alopecia. Complete hair loss was noted over the head, neck, shoulder, thigh, and proximal limbs, but the trunk, distal limbs, pelvic area, mane, and tail were unaffected. The alopecic areas were visually noninflammatory with no exudate or crust except on the shoulder and along the back, where multifocal patchy areas of alopecia with scales and crust were evident. The horse was slightly pruritic. Microscopically, the hair bulbs, inner and outer root sheaths of inferior segments, and perifollicular regions were infiltrated by small to moderate numbers of small lymphocytes. Similar inflammation was occasionally evident in isthmus follicular walls as well as some apocrine glands. No sebaceous glands were affected. Immunohistochemistry confirmed that the small lymphocytes were CD3(+) T lymphocytes. The epidermis from the skin with scale and crusts along the horse's back exhibited mild to moderate hyperplasia, mild lymphocytic exocytosis, mild eosinophilic dermatitis, and diffuse parakeratosis with numerous budding yeasts, consistent with Malassezia spp. The final disease diagnosis was made as alopecia areata with Malassezia dermatitis. Alopecia areata could be a contributing underlying factor for Malassezia dermatitis.     

Rat lymphocytic thyroiditis associated with ingestion of an immunosuppressive compound

Lymphocytic thyroiditis was induced in young Wistar rats by feeding them the immunosuppressive compound frentizole [1-(6-methoxy-2-benzothiazolyl)-3-phenyl urea] for 1 year. About half of the rats given 0.060 and 0.150% frentizole in the diet had lymphocytic thyroiditis. The incidence of thyroiditis was low in the group given the high dose because of severe anemia and hepatic disease which resulted in increased mortality. Reversibility of the thyroid lesion was indicated by reduced incidence rates at 15 and 18 months after treatment was stopped at 1 year. The thyroiditis was characterized by interstitial infiltrates of many lymphocytes and plasma cells and fewer macrophages with mild degenerative changes in the follicular epithelium. This inflammatory cell infiltrate was generally diffuse but occasionally was multifocal, particularly in thyroid glands of rats late in the reversibility phase of the study. The inflammatory cell infiltrate caused the thyroid glands to be several times normal size. Sera from rats with lymphocytic thyroiditis contained hemagglutinating antibody against rat perfect correlation between the presence of anti-thyroglobulin antibody and enlarged thyroid glands. Fine granular deposits of IgG and complement were identified in some areas of the follicular basement membrane. We concluded that the lymphocytic thyroiditis was immunologically mediated, at least in part, by anti-thyroglobulin antibody.     

Alopecia areata with lymphocytic mural folliculitis affecting the isthmus in a thoroughbred mare

A 13-year-old, thoroughbred mare was presented with an 8-year history of multifocal, generalized, noninflammatory alopecia and a 3-month history of alopecia, erythema and scaling of the white star on the forehead and muzzle. Histopathological examination of biopsy samples from multiple sites on the body (mane, neck, shoulder, flank and gluteal region) showed a subtle lymphocytic inflammatory infiltrate affecting and surrounding the anagen hair bulbs, consistent with a diagnosis of alopecia areata. The biopsy sample from the star on the forehead showed atrophic hair follicles with perifollicular and mural mononuclear folliculitis affecting the isthmus. Immunohistochemical staining with a CD3 marker confirmed the T-lymphocytic origin of the inflammatory infiltrate in all the samples. The concurrent presence of lymphocytic infiltration at the bulbar and isthmic level of the hair follicles in the same horse is unusual. This finding may represent a variation of the histological appearance of alopecia areata.