Rationale: In adults, hydroxychloroquine is one anti-inflammatory steroid-sparing agent used to treat chronic idiopathic urticaria (CIU) refractory to antihistamines. Whether hydroxychloroquine is safe and effective for antihistamine-refractory CIU in children is unknown.
Methods: We present an infant with resolution of antihistamine-refractory CIU following treatment with hydroxychloroquine and concomitant discontinuation of steroids.
Results: A 9-month-old male infant presented with a 5-month history of recurrent unprovoked urticaria and angioedema of the hands and feet refractory to high-dose H1 and H2 antihistamines and leukotriene antagonists. Physical examination revealed diffuse pleomorphic urticaria and marked dermatographism. Laboratory testing demonstrated an elevated platelet count (534,000/microliter) and C-reactive protein (CRP, 2.0 mg/dL). Serum tryptase, C3, C4, and C1q were normal. Antinuclear, anti-thyroid, and anti-IgE receptor antibodies were negative; cow’s milk specific IgE was undetectable. Skin biopsy showed perivascular lymphocytic infiltrate, perivascular to interstitial eosinophils, no neutrophilic infiltrate or evidence of urticarial vasculitis. Symptoms were moderately well controlled by adding oral prednisolone (0.65 mg/kg) every other day but rebounded if steroids were tapered further. Hydroxychloroquine 2mg/kg/day was initiated and up-titrated to 6 mg/kg/day over 3 months, and platelet count and CRP normalized. Adverse reactions included diarrhea that resolved with dose modification. After 3 months of hydroxychloroquine (at age 12 months), prednisolone taper was initiated. Prednisolone was discontinued by age 14 months without recurrence of urticaria or angioedema.
Conclusions: While further study is needed, we demonstrate that hydroxychloroquine can be a safe and effective treatment for antihistamine-refractory CIU in children, leading to down-titration and subsequent cessation of systemic steroid therapy.