A case of hypocomplementaemic urticarial vasculitis in a child due to coxsackievirus type A9

Abstract

Background: Urticarial vasculitis is characterised by episodes of uncontrollable urticaria and by biopsy evidence of leukocytoclastic vasculitis. It has been reported to accompany infection, malignancy, connective tissue diseases such as systematic lupus erythematosus(SLE), viral hepatitis, and cryoglobulinemia, and the administration of certain drugs. Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a type III allergic reaction characterised by urticaria with persistent hypocomplementemia. HUVS has been frequently been described in adults, but is very rare in children. Method: We examined a 1-year-old girl who presented with continuous fever and multiple urticarial rashes and wheals on her face, trunk, back and limbs. Treatment with an antihistamine was ineffective. We performed a skin biopsy to examine pathologic tissue, and collected specimens by nasopharyngeal swab specimens as well as stool and blood specimens for microbiological examination using MRC-5 (human embryo lung fibroblast) cells. Results: Laboratory tests revealed the following findings: white blood cell (WBC) count, 21 200/ll (neutrophilis 76%), total protein, 5.6 g/dl, albumin, 2.8 g/dl, FDP 12.8 μg/dl, D-dimer, 9.1 μg/dl, and C reactive protein, 13.55 mg/dl. The C3 level, (16 mg/dl), C4 level, (1 mg/dl), CH50 level, (5.9 mg/dl), and C1q level (1.5 μg/ml) were extremely low. Antinuclear antibody (ANA) was not detected. At first, we thought that the patient had Kawasaki disease, but a skin biopsy revealed early lesion of leukocytoclastic vasculitis. Permeation of lymphocytes and histocytes with nuclear dusts (products of the destruction of neutrophil nuclei), eosinophiles and neutrophils had occurred around the superficial dermal blood vessels, and leakage of the blood cells from the capillary vessels was observed. These findings led to a diagnosis of HUVS. We therefore treated her with prednisolone 2 mg/kg/day, gradually reducing the dose after the urticaria had disappeared. We isolated coxsackievirus type A9 (CA9) from the all samples (nasal fluid, blood, and stool). The neutralising antibody against CA9 in the convalescent phase serum was significantly more elevated than that in the acute phase serum. Conclusion: Infection by the coxsackievirus type A9 may cause HUVS.