Interleukin-6 Inhibitor-Induced Leukocytoclastic Vasculitis: A Case Report With a Literature Review.

Background: Leukocytoclastic vasculitis (LCV) is a known hypersensitivity reaction to biologic agents, often linked to tumor necrosis factor-α (TNF-α)inhibitors. We present a rare case of LCV in a patient receiving tocilizumab, a monoclonal antibody directed against interleukin-6 (IL-6)receptor. Case presentation: A 33-year-old Asian female with seropositive rheumatoid arthritis presented to the rheumatology clinic complaining of a new rash that started a few days after an infusion of tocilizumab. Her rheumatoid arthritis had been managed with upadacitinib for several years, which was discontinued due to persistent transaminitis. She was started on tocilizumab after a 4-month break from biologics. Following the first tocilizumab infusion, she recalled having transient fatigue and several red dots on her forearms and feet. A few days after the second infusion, she developed a purpuric rash on her lower extremities and forearms. Skin biopsy confirmed LCV. The rash resolved slowly in a month after discontinuation of tocilizumab and prescription of prednisone 20 mg daily. At her 3-month follow-up, the patient remained in remission, and her rheumatoid arthritis was uneventfully managed with abatacept. Conclusions: While most cases of biologic-associated LCV are induced by TNF-α inhibitors, only two known cases of tocilizumab-induced hypersensitivity vasculitis have been published in the literature. Our case represents only the third reported instance in the literature, highlighting the need to raise awareness of tocilizumab as a potential cause of leukocytoclastic vasculitis and the importance of prompt recognition and management.