Urticarial Reaction to Ustekinumab During the Treatment of Plaque Psoriasis in a Hepatitis C-Positive Patient.

A 62-year-old white woman with a history of hepatitis C and type 2 diabetes mellitus developed urticaria during treatment with ustekinumab for plaque psoriasis. The patient received two 45-mg ustekinumab injections in her first 2 months and then one 45-mg injection every 3 months for her psoriasis. After 10 months, she developed a round red rash on her skin diffusely on her body. She also complained of joint pain in her hands. Rheumatology became involved, and investigations revealed that her antinuclear antibody titer was negative, but her rheumatoid factor, erythrocyte sedimentation rate, and liver function enzymes were elevated. She was diagnosed with urticaria, and ustekinumab was discontinued. A Naranjo assessment score of 6 was obtained, indicating a probable relationship between the patient's urticaria and her use of ustekinumab. Ustekinumab was subsequently discontinued, and the patient received a course of Harvoni^® (Gilead Sciences, Inc., Forest City, California, United States) (ledispasvir/sofosbuvir) with clearance of the hepatitis C virus. The patient is currently receiving another biologic agent, ixekizumab, and reports no complaints, including that of urticaria.