Childhood polyarteritis nodosa (PAN) is a necrotizing vasculitis, affecting small and medium size blood vessels. This condition was first described by Kussmaul and Maier in 1866. Although comparatively rare in childhood, it is the most common form of systemic vasculitis in children. PAN includes two different subtypes, the classical systemic form presenting with a wide range of clinical manifestations including dermatologic, musculoskeletal, nervous, renal, and gastrointestinal systems and the more frequent cutaneous form (CPAN) that involves only the skin. The main clinical features of PAN are malaise, fever, weight loss, skin rash, myalgia, abdominal pain and arthropathy. Systemic involvement is variable, but the skin, the musculoskeletal system, the kidneys and the gastrointestinal tract are most prominently affected, with cardiac, neurological and respiratory manifestations occurring less frequently. However, clinical manifestations can be very confusing, with absence of conclusive diagnostic evidence in the early phase and sometimes in the late phase of the illness. The etiology of PAN remains unclear, but there are data to support roles for hepatitis B and reports of a higher frequency of exposure to parvovirus B19 and cytomegalovirus in PAN patients compared with control populations. However, in childhood, associations between PAN and these infections or other conditions are rare. Evidence has emerged suggesting that bacterial superantigens may play a role in some cases. Here we report the clinico-pathological findings of a 21-month-old child affected with PAN, with particular emphasis on the severity of renal pathological lesions.