Abstract: This case involved a 10-year-old female patient who presented with a 46-day history of intermittent fever and cough. Chest computed tomography（CT） revealed multiple thick-walled cavitary lesions and nodular opacities in both lungs. Polymicrobial bacterial infection was identified by etiological testing，and the provisional diagnosis was pneumonia with lung abscess. The patient's condition initially improved after anti-infective therapy but relapsed rapidly，with the subsequent gradual development of multisystem involvement manifestations including anemia，oral ulcers，skin rashes and purpura. After 58 days of complicated diagnosis and treatment，the patient was definitively diagnosed with granulomatosis with polyangiitis（GPA） via vasculitis-related antibody testing，skin tissue biopsy，and multidisciplinary team（MDT）consultation. The core value of this case lies in revealing the atypical onset characteristics of rare pediatric autoimmune diseases，highlighting the diagnostic challenges when infection is intertwined with autoimmune lesions，and emphasizing the importance of multidisciplinary collaboration，dynamic monitoring of inflammatory markers and timely completion of specific examinations in avoiding misdiagnosis.

Key words: lung abscess, pneumonia, childhood systemic vasculitis, ANCA-associated vasculitis, granulomatosis with polyangiitis

摘要： 1例 10 岁女性患儿，以“间断发热、咳嗽46d”起病，胸部计算机断层扫描（CT）检查提示双肺多发厚壁空洞影及结节影，病原学检出多重细菌感染，初步诊断为“肺炎、肺脓肿”，经抗感染治疗后病情一度缓解但迅速复发，且逐渐出现贫血、口腔溃疡、皮疹、紫癜等多系统受累表现。历经58 d 诊疗波折，通过血管炎相关抗体检测、皮肤组织活检联合多学科诊疗（MDT）明确诊断为肉芽肿性多血管炎。该例的核心价值在于揭示了儿童罕见自身免疫性疾病的不典型起病特点，凸显了感染与自身免疫病变交织时的诊断难点，强调了 MDT、动态监测炎症指标并及时完善特异性检查对避免误诊的重要意义。

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