Leukocytoclastic Vasculitis Associated with Influenza A Virus Infection
A 2-yr-old Korean girl visited for purpuric skin lesions on June 24, 2011. She was previously healthy and weighed 12 kg. One week before, she had clear rhinorrhea without sore throat, cough or fever. Afterward, the lesions were firstly observed on the lower legs 4 days ago and had been rapidly extended to face and upper extremities with fever. She had none of any known disease and no history of drug medication or allergy.\nAt admission, she looked sick with a body temperature of 38.4℃ and did not complain of abdominal pain or arthralgia. On examination, she presented multiple rice grain to walnut sized palpable purpuric and hemorrhagic lesions on the face and extremities () without heatness or tenderness on palpation. The lesions were variable sized, some lesions were reticulated.\nLaboratory tests showed leukocytosis (white blood cells 19,230/µL: neutrophils 16,150/µL [84%]), elevated C-reactive protein (4.825 mg/dL), elevated D-dimer (12.016 µg/mL), and decreased partial thromboplastin time (21.9 sec). Liver function test and urine analysis were within normal limits. Specific laboratory studies for ruling out immunological and autoimmune disorder including anti-nuclear antibody (ANA), anti-double stranded DNA antibody, anti-neutrophilic cytoplasmic antibody (ANCA), anti-Ro antibody, anti-La antibody, anti-Scl antibody, anti-Smith antibody, rheumatoid factor, and cold agglutinin test were within normal limits or negative. Also, chest X-ray was normal and blood culture for bacteria revealed no growth. Then, skin biopsy was done on the right lower leg.\nHistopathologic finding revealed perivascular inflammatory cell infiltrations in the dermis (). On the high-power view, perivascular neutrophilic infiltrations with nuclear dusts, extravasated red blood cells, and fibrin deposition of the small vessel wall were observed (). Immunofluorescence studies of specimen including IgG, IgA, IgM, and C3 were negative.\nWith these clinical, laboratory, and histopathologic findings, leukocytoclastic vasculitis due to bacterial infection was suspected and prednisolone (4 mg three times a day, orally) and cephalosporin (450 mg twice a day, intravenously) were administered. Despite the treatment for 3 days, new vasculitic lesions occurred, and the body temperature did not return to normal.\nOn hospital day 4, influenza A virus was isolated from nasopharyngeal swab by reverse-transcriptase polymerase chain reaction (RT-PCR) assay which was performed at admission. Then, cephalosporin was stopped and oseltamivir (Tamiflu®, 30 mg twice a day, orally) was added immediately for 5 days. Although her body temperature returned to normal in 24 hr, new vasculitic lesions were persistently developed. Dose of prednisolone increased up to 24 mg and there was significant improvement of the vasculitic lesion after three days. On hospital day 12, all skin lesions were disappeared and she was discharged to home. No recurrence of vasculitic skin lesions was observed for 2 months of follow-up.