SUMMARY: Cat scratch disease (CSD) is an infectious disease caused by Bartonella henselae. Atypical clinical presentations of CSD include prolonged fever and multiple hepatosplenic lesions. Furthermore, multiple renal lesions are extremely rare in CSD. An 11-year-old Japanese girl presented at our hospital with a prolonged fever of unknown cause after being scratched and bitten by a kitten. Abdominal computed tomography (CT) revealed multiple small, round hypodense lesions in both kidneys and the spleen. Based on her history and the CT results, her diagnosis was CSD. The diagnosis was confirmed by serological tests, which indicated antibodies against B. henselae. After treatment with azithromycin, her fever immediately improved. Careful history taking and imaging are essential for the diagnosis of atypical CSD. In CT images, not only hepatosplenic lesions but also renal lesions are important features indicative of a diagnosis of atypical CSD. Subsequently, a diagnosis of CSD can be confirmed by specific serological tests. This is the first reported Japanese case of multiple renal and splenic lesions in a patient with CSD. Although difficult to diagnose, an early diagnosis atypical CSD and appropriate treatment are important to prevent complications and the need for invasive examinations.Cat scratch disease (CSD), which is generally seen in children, is an infectious disease caused by Bartonella henselae, a gram-negative bacillus (1). Typical CSD is generally benign and self-limiting. CSD is characterized by regional lymphadenopathy with fever following a scratch or bite from a cat or kitten. However, certain CSD cases may present with atypical symptoms. Atypical CSD clinical presentations might include prolonged fever and multiple hepatosplenic lesions (2). On the other hand, multiple renal lesions are extremely rare in CSD (3). Here, we present the case of a child with atypical CSD, who had multiple renal and splenic lesions.A previously healthy 11-year-old Japanese girl presented to our hospital with a fever of unknown cause. Empiric antibiotics (oral clarithromycin 10 mg/kg/day for 9 days, oral minomycin 4 mg/kg/day for 5 days, and intravenous ceftriaxone 75 mg/kg/day for 5 days) were administered before she visited our hospital, but the fever persisted. She had a 1-month history of a persistent fever at night (her temperature rose to 39-409 C at night and dropped to 36-379 C during the daytime) after being scratched and bitten by a kitten.On physical examination, neck lymphadenopathy with minimal pain was observed. Routine laboratory test results, including a complete blood count, hepatic and renal function tests, and urinalysis, were normal; however, she had a high C-reactive protein level (4.57 mg/dL; reference range [rr], <0.27 mg/dL) and an increased erythrocyte sedimentation rate (ESR, 74 mm/h; rr, 5-15 mm/h). Serum immunoglobulin (Ig) A and IgM levels were normal; however, she had high IgG (1,921 mg/dL; rr, 870-1,700 mg/dL) and complement (C3, 186 mg/dL; C4, 38 mg/dL; and CH50, 50 U/mL; rr's, 65-135 mg...