Oclacitinib as a corticosteroid-sparing agent in a cat with pemphigus foliaceus: A case report

다국어 초록 (Multilingual Abstract)

A 4-year-old neutered male Scottish Fold cat presented with severe crusting and erythema of the periorbital region, muzzle, chin, and pinnae with marked pruritus. Dermatophyte culture and fungal PCR were negative. Cytologic examination of impression smears revealed numerous non-degenerate neutrophils and acantholytic keratinocytes, strongly supporting a diagnosis of pemphigus foliaceus (PF). Because of financial constraints, skin biopsy was initially deferred and empirical immunosuppressive therapy with systemic glucocorticoids and cyclosporine was started. The lesions improved transiently but recurred after tapering prednisolone. At that time, a skin biopsy was performed; histopathology disclosed erosive to ulcerative dermatitis without subcorneal pustules or acantholysis, findings considered to have been masked by prior immunosuppressive therapy. Based on the typical lesion distribution and cytologic findings, PF remained the most likely diagnosis. Because the lesions recurred when prednisolone was tapered despite ongoing cyclosporine therapy, cyclosporine alone was considered insufficient to maintain disease control. The protocol was therefore modified by discontinuing cyclosporine and introducing oclacitinib, a Janus kinase-1–biased inhibitor targeting pruritogenic and pro-inflammatory cytokines, together with a rapidly tapered course of prednisolone.
This regimen led to rapid and sustained lesion control, allowed early discontinuation of corticosteroids, and maintained six months of remission with oclacitinib monotherapy without apparent adverse effects. This case suggests that oclacitinib can be used as a corticosteroid-sparing option in feline PF and emphasizes the importance of performing skin biopsy before starting immunosuppressive treatment.