Resolution of Superimposed Linear Psoriasis With Bimekizumab After Resistance to Several Biologics.

Superimposed linear psoriasis is an uncommon form of psoriasis characterized by linear skin lesions aligned with Blaschko's lines, appearing in conjunction with typical psoriatic plaques. This variant is believed to involve cutaneous mosaicism and often shows differential treatment responses between linear and conventional lesions. We present the first case of superimposed linear psoriasis that was resistant to several biologic agents but responded favorably to bimekizumab, a monoclonal antibody targeting both interleukin (IL)-17A and IL-17F. A 33-year-old Japanese male with widespread plaque psoriasis developed a persistent, itchy linear lesion on his right thigh despite prior treatment with cyclosporine and multiple biologics, including ustekinumab, guselkumab, and risankizumab. While generalized psoriasis improved with IL-23 inhibitors, the linear component remained unaffected. Upon initiating bimekizumab at age 45, the patient achieved remission of classical plaque psoriasis within four weeks, and the linear lesion showed marked improvement over a year. This case highlights the potential utility of dual IL-17A/F inhibition in treating this rare and difficult-to-manage psoriasis subtype and suggests a need for further clinical evaluation in larger patient populations.