Antisynthetase Syndrome Masquerading As Psoriasis and Psoriatic Arthritis: A Case Report

Antisynthetase syndrome (ASyS) is a subtype of idiopathic inflammatory myopathy. It may have cutaneous findings like psoriasis and dermatomyositis, making clinical diagnosis challenging. We report a case of a 49-year-old woman who presented with initial symptoms of psoriasis and psoriatic arthritis: scaly patches on the scalp, scaly patches on the elbows, hyperkeratotic scaly plaques on her palms, and inflammatory joint symptoms. However, the development of phototherapy-induced flares and resistance to topical steroids prompted reconsideration of her diagnosis. Further investigations revealed the presence of anti-Jo-1 antibodies, which led to the diagnosis of ASyS. This case emphasizes the need for a broad differential diagnosis when evaluating psoriasiform skin changes, particularly in cases with atypical features or resistance to standard treatments.