Initial Management of Pediatric Vasculitis
The initial management of pediatric vasculitis depends critically on the specific type: Kawasaki disease requires immediate IVIG 2 g/kg plus high-dose aspirin within 10 days of fever onset, while ANCA-associated vasculitis demands urgent combination therapy with IV methylprednisolone followed by oral glucocorticoids plus either rituximab or cyclophosphamide. 1
Kawasaki Disease Management
Immediate Treatment Protocol
- Administer IVIG 2 g/kg as a single infusion within 10 days of fever onset to reduce coronary artery aneurysm risk from 25% to 5% 2, 1
- Start high-dose aspirin 80-100 mg/kg/day divided into 4 doses until fever resolves for 48-72 hours 2, 1
- All patients meeting diagnostic criteria should be treated as soon as the diagnosis is established 2
Critical timing consideration: Even patients presenting after day 10 of illness should receive IVIG if they have ongoing systemic inflammation (CRP >3.0 mg/dL) or coronary artery abnormalities 2
Post-Acute Phase Management
- After fever resolution, reduce aspirin to 3-5 mg/kg/day (antiplatelet dose) and continue for 6-8 weeks if no coronary abnormalities are present 2, 1
- If coronary aneurysms develop, continue low-dose aspirin indefinitely 2, 1
- For moderate or giant coronary aneurysms, add warfarin to low-dose aspirin as primary thromboprophylaxis 2
Important Safety Precautions
- Defer measles and varicella immunizations for 11 months after high-dose IVIG 1
- Avoid ibuprofen in children with coronary aneurysms taking aspirin, as it antagonizes aspirin's irreversible platelet inhibition 1
- Administer annual inactivated influenza vaccine to all children on chronic aspirin therapy to prevent Reye syndrome risk 1
ANCA-Associated Vasculitis (GPA/MPA)
Induction Therapy for Severe Disease
For severe presentations with renal impairment or pulmonary hemorrhage, initiate IV pulse methylprednisolone 30 mg/kg/day (maximum 1,000 mg/day) for 3 doses prior to starting rituximab or cyclophosphamide 1, 3
- Following IV pulse therapy, transition to oral prednisone 1-2 mg/kg/day (maximum 60 mg/day) 1, 3
- Taper glucocorticoids to 0.2 mg/kg/day (maximum 10 mg/day) by month 6 1, 3
Rituximab Protocol (Preferred for Pediatric Patients)
The FDA-approved pediatric regimen consists of four once-weekly IV infusions of rituximab at 375 mg/m² BSA on days 1,8,15, and 22 3
- Administer a minimum of 3 doses of IV methylprednisolone (30 mg/kg/day, not exceeding 1g/day) prior to the first rituximab infusion 3
- After the 6-month remission induction phase, patients may receive subsequent rituximab infusions every 6 months to maintain remission 3
- In the pivotal pediatric trial, 56% achieved remission by month 6,92% by month 12, and 100% by month 18 3
Cyclophosphamide Alternative
- For patients where rituximab is unavailable, use cyclophosphamide 2 mg/kg/day orally plus glucocorticoids 1 mg/kg/day 4
- The combination of cyclophosphamide and glucocorticoids is the standard induction regimen for generalized and severe disease 4
Mandatory Supportive Care
All patients on cyclophosphamide or rituximab require Pneumocystis jiroveci prophylaxis with trimethoprim/sulfamethoxazole 2, 1
- Administer mesna with cyclophosphamide to prevent hemorrhagic cystitis 4
- Monitor complete blood count, renal function, blood glucose, and urinalysis regularly 4
Treatment Monitoring
- Do not delay treatment while waiting for biopsy results in rapidly deteriorating patients 1
- Monitor ANCA levels during treatment, as persistence or increase may predict future relapse 1
Polyarteritis Nodosa
Severe Disease Protocol
Initiate IV pulse methylprednisolone 30 mg/kg/day (maximum 1,000 mg/day) for 3-5 days 1
- Combine glucocorticoids with cyclophosphamide plus high-dose oral prednisone (1-2 mg/kg/day, maximum 60 mg/day) for severe disease 1
- Obtain abdominal vascular imaging to establish diagnosis and extent of disease 1
- For suspected cases with skin involvement, obtain deep-skin biopsy reaching medium-sized vessels rather than superficial punch biopsy 1
Common Pitfalls to Avoid
The most critical error is delaying IVIG treatment in Kawasaki disease beyond day 10 of fever, as this significantly increases coronary artery aneurysm risk from 5% to 25% 2, 1. The incomplete presentation algorithm should be applied liberally given the low risks of IVIG administration versus the high risks of untreated disease 2.
For ANCA-associated vasculitis, glucocorticoid-related infections are a leading cause of death in the first year, making dose minimization and prophylactic antimicrobials essential 5. The PEXIVAS trial demonstrated that reduced-dose glucocorticoid regimens with rapid tapering are as effective as standard regimens but safer 5.
Never use ibuprofen concurrently with aspirin in Kawasaki disease patients with coronary involvement, as NSAIDs antagonize aspirin's antiplatelet effects 1. This is a frequently overlooked drug interaction with potentially serious consequences.