An unresponsive progressive pustular and crusting dermatitis with acantholysis in nine cats

Abstract

Background Between 2000 and 2012, nine cats were examined with a visually distinctive, progressive crusting dermatitis that was poorly responsive to all attempted therapies. Objectives Documentation of clinical and histopathological findings of this disease. Animals Nine privately owned cats. Methods Retrospective study. Results Eight neutered males and one (presumably spayed) female ranging in age from two to eight years, presented for a progressive, well‐demarcated, crusting dermatitis with variable pruritus of 1.5 months to five years duration. All cats lived in northern California, USA; seven lived within a 30 mile radius. Two males were littermates. Histopathological investigation showed both parakeratotic and orthokeratotic crusts, intraepidermal pustules and superficial folliculitis with rare to frequent acantholytic cells. Bacterial and fungal cultures were performed in six cats: meticillin‐susceptible Staphylococcus pseudintermedius was isolated in three cats, two colonies of Trichophyton terrestre and three of Malassezia pachydermatis were isolated from one cat each. Treatment with various antibiotics, antifungal and a variety of immunosuppressive medications did not alter the progressive nature of the skin disease. Conclusions and clinical importance The described disease shares some clinical and histopathological features with pemphigus foliaceus, but the lack of response to treatment, its progressive nature and the possible relatedness of some of the cats set it apart. The aetiology of this acantholytic dermatitis remains unknown.

Clinicopathological findings and clinical outcomes in 49 cases of feline pemphigus foliaceus examined in Northern California, USA (1987–2017)

“…When provided with the opportunity to share additional details relevant to the management of PF: three of 23 owners (13%) expressed the time leading up to diagnosis and complete remission to be the most stressful; two of 23 owners (9%) expressed regret for pursuing treatment and not considering humane euthanasia earlier; one of 23 owners (4%) reported experiencing stress with entrusting care to another person while travelling as the cat would not easily take medications from others; and one of 23 owners (4%) reported developing a closer bond with her cat through providing intensive care and treatment. Interestingly, one of 23 cats (4%) was noted to cohabit with another unrelated cat diagnosed with an unresponsive progressive pustular and crusting dermatitis with acantholysis described in a case series …”

Pathology in Practice

“…Case summary: taking into consideration the patient's history, clinical signs, and poor response to treatment, the skin lesions were most consistent with progressive pustular and crusting dermatitis and acantholysis previously reported in 9 cats from Northern California. 1…”

“…Recently, a poorly understood, recalcitrant, progressive, acantholytic pustular, and crusting dermatitis was described in 9 cats examined in Northern California over a 14-year period. 1 Clinical lesions were characterized by asymmetric, well-demarcated, markedly adherent crusting with variable alopecia and reportedly originated from a single digit, paw, or limb in 5 cats, the face or head in 3 cats (33%), and the chin and a single paw in 1 cat. Skin lesions progressed to involve the entire limb in all cats with initial involvement of a single digit or paw.…”

“…Although the etiology and pathogenesis of this disease entity remains poorly understood, it has been speculated to represent either a genodermatosis (ie, a hereditary skin disease), a regional infectious disease, or an immunologic response following exposure to an ectoparasite endemic to Northern California. 1 Evaluating sera for the presence of autoantibodies targeting desmosomal proteins and performing metagenomic analyses on fresh skin samples could offer insight into an immune-mediated process or potential infectious etiology, respectively.…”