A 3‐month‐old otherwise healthy girl presented with 5 days of fevers, decreased oral intake, and fatigue. She was treated with amoxicillin for a presumed streptococcus pharyngitis infection, but development of periorbital erythema and rash prompted evaluation at another hospital. There, she had edema of her hands and feet, a maculopapular rash of the palms and soles with desquamation, and conjunctivitis. She was initially diagnosed with Kawasaki Disease (KD), given evidence of coronary artery aneurysms on echocardiogram. Despite treatment with high dose aspirin, steroids, and IV immunoglobulin (IVIg), her fevers persisted. She was transferred to our hospital where she had a temperature of 38.5 degrees Celsius, tachycardia and tachypnea. She was fussy with conjunctivitis and a maculopapular rash involving the palms, soles, and right infraorbital region. Labs showed a white blood cell count of 30.3 k/ul, hematocrit of 31.8 g/dl, platelets of 106 k/ul, and C‐reactive protein (CRP) of 8.3 mg/dl. An infectious workup including viral studies and blood, urine, and cerebrospinal fluid cultures was negative. Her fevers persisted for 27 days with worsening coronary aneurysms and rising CRP levels. Under the guidance of a Rheumatology consult, she received additional steroids, aspirin, anikinra and infliximab. Her fevers and rising CRP levels finally responded to cyclophosphamide. Follow‐up magnetic resonance imaging/magnetic resonance angiogram showed dilatation of the axillary and brachial arteries, suggestive of systemic vascular inflammation. The refractory nature of her disease and extracoronary vascular involvement led to the ultimate diagnosis of infantile polyarteritis nodosa (PAN).
KD and infantile PAN are disseminated vasculitides affecting small and medium sized vessels. Though distinct entities, KD and PAN exhibit overlapping clinical and pathological features that make appropriate diagnosis and treatment challenging, particularly in cases presenting as atypical or incomplete KD. Fever, rash and acute necrotizing arteritis with aneurysm formation can be seen in both. Histiologically, KD has a predilection for coronary arteries with invasion of macrophages and T‐lymphocytes whereas PAN is characterized by neutrophil activation and fibrinoid necrosis. Occasional coronary involvement occurs in PAN, but aneurysms are frequently seen in the gastrointestinal and renal organs as well. KD is treated with high dose aspirin and IVIg, whereas corticosteroids and immunosuppressive agents are used to treat PAN. When severe manifestations of systemic vasculitis are present, lack or significant delay of proper treatment can result in heart failure, renal failure, severe gastrointestinal disturbance, and central nervous system dysfunction.
KD and PAN are systemic vasculitides with a wide range of clinical, and often overlapping, features. Treatment should be tailored according to the severity of such manifestations.