Polyarteritis nodosa: A contemporary overview.

Polyarteritis nodosa (PAN) is a systemic necrotizing vasculitis predominantly targeting medium-sized arteries. PAN is a rare form of vasculitis, and the precise frequency of this disease is difficult to determine. The major environmental factor associated with PAN is HBV infection. The pathogenesis of "idiopathic PAN" remains enigmatic, although the clinical responses to immunosuppressive therapy support the concept that immunological mechanisms play an active pathogenic role. The spectrum of disease ranges from involving a single organ to polyvisceral failure. Any organ might be affected; however, for reasons that are not understood, PAN does not affect the lungs. In addition to the systemic idiopathic form, called "idiopathic generalized PAN," there are 2 clinical variants of this disease: "cutaneous PAN" and "hepatitis B virus (HBV)-associated PAN". Diagnosis requires the integration of clinical, angiographic, and biopsy findings. The overall prognosis of this disease has been improved in recent decades, primarily reflecting early diagnosis and more effective treatments. Idiopathic generalized PAN should be treated with a combination of glucocorticoids and cyclophosphamide. The treatment of HBV-associated PAN involves a different approach, centered on the use of an antiviral agent to control the infection. The therapy for cutaneous PAN requires a less aggressive approach based on the administration of non-steroidal anti-inflammatory drugs over short periods of time.