Clinical and histological recovery of non-thymoma-associated exfoliative dermatitis in a cat treated with ciclosporin A

Abstract

Case summary A 6-year-old neutered female European Shorthair cat was referred for chronic, moderately pruritic, alopecic and exfoliative dermatosis that was unresponsive to antiparasitic, antibiotic or steroidal anti-inflammatory drugs. The cat presented with truncular alopecia and numerous whitish adherent scales covering the whole body. Differential diagnoses included sebaceous adenitis, dermatophytosis, demodicosis, exfoliative dermatitis associated or not with thymoma, drug reaction, feline immunodeficiency virus- or feline leukaemia virus-associated dermatoses, epitheliotropic T-cell lymphoma, and Malassezia yeasts and/or bacterial overgrowth. Blood tests were within normal limits and the retrovirus tests were negative. Skin scrapings, fungal culture, coat brushing and skin cytology were negative for parasitic or microbial elements. Radiographs showed no signs of a thymic mass. Histological examination of skin biopsies revealed marked orthokeratotic hyperkeratosis, lymphocytic (CD3+) interface dermatitis and mural folliculitis with absence of sebaceous glands and occasional apoptotic cells in different epidermal layers. Clinical and histological findings were consistent with non-thymoma-associated exfoliative dermatitis syndrome. Ciclosporin A (7 mg/kg) was administered once daily. A dramatic improvement was observed after 3 weeks. Ciclosporin A intake was then progressively spaced out as the clinical signs diminished. Skin biopsies revealed resolution of hyperkeratosis, disappearance of the inflammatory infiltrate and recovery of the sebaceous glands. Relevance and novel information T-cell infiltration with signs of epidermal cytotoxicity, in the absence of infectious agents or neoplastic process, suggests an immune-mediated process, and ciclosporin A, a calcineurin inhibitor, would be the drug of choice. This is the first report showing resolution of both the clinical and histological signs of non-thymoma-associated exfoliative dermatitis.

Non‐thymoma‐associated exfoliative dermatitis in a European shorthair cat: A case report

“…Hence, LE and EM were excluded as possible diagnoses. The most important clinical symptom reported in previous case studies was generalized or, less frequently, localized exfoliation with local or generalized alopecia (Combarros et al, 2020). The histopathological findings in the present case were consistent with the findings reported in previous literature, namely, orthokeratotic hyperkeratosis, lymphocytic interface dermatitis, mural folliculitis with the presence of apoptotic cells, and sebaceous adenitis (Linek et al, 2015, Combarros et al, 2020.…”

“…Only the simultaneous application of the pharmacotherapeutic agents was observed to be effective, which is consistent with the cases reported by Linek et al. Generally, improvement in exfoliative dermatitis is observed after several months of therapy (Linek et al., 2015 , Combarros et al., 2020 ). Occasionally, the disease resolves after the use of antibiotics, shampoo therapy, or spontaneously (Linek et al., 2015 ).…”

“…The current case report describes a case of exfoliative dermatitis that was not associated with thymoma, which is extremely rare in cats; thus far, only a few cases have been reported in literature (Linek et al, 2015, Combarros et al, 2020. The diagnosis was established on the basis of the clinical picture and the results of the histopathological examination.…”

“…In the cases reported and discussed by Linek et al., treatment using prednisolone, methylprednisolone, or dexamethasone was reported to be effective in feline patients (Linek et al., 2015 ). Apart from glucocorticosteroids, cyclosporine (at a dose of 7 mg/kg body weight/day) was also used in the treatment as a sole therapeutic agent (Combarros et al., 2020 ) or in combination with the glucocorticosteroids (Linek et al., 2015 ). In the current case, the symptoms did not resolve after monotherapy using prednisolone.…”

“…In addition, other neoplasms, drug reactions, and nutritional factors have been reported as syndrome‐triggering agents (Pascal‐Tenorio et al., 1997 , Gross et al., 2005 , Declercq, 2000 ). Moreover, literature has described numerous cases of the disease without the identification of the factors that could be responsible for the development of dermatitis (Linek et al., 2015 , Combarros et al., 2020 ). Regardless of the etiology, the syndrome displayed concurrent histopathological features.…”