Drug-Induced Vasculitis

An increasing array of drugs can induce vasculitis, a process which causes necrotizing inflammation of vessels and, in turn, tissue ischaemia and inflammation. While most cases will be mild, presenting with arthralgia, malaise and cutaneous leucocytoclastic vasculitis, some cases can be severe and cause major organ involvement, critical illness and rarely death. Clinicians therefore need to be vigilant for systemic disease involvement, stop the offending agent promptly and initiate immunomodulatory therapy when necessary. Novel cancer immunotherapeutic agents such as checkpoint inhibitors (CPIs) are associated with a growing spectrum of rheumatic side effects, including vasculitis. Collectively, these are termed immune related adverse events (irAEs). In this chapter, the drugs most frequently associated with drug-induced vasculitis are discussed, known pathogenic mechanisms are explored, and a clinical approach to diagnosis and management is outlined.