肺诺卡菌病（PN）是由诺卡菌导致的严重的肺部感染性疾病，临床少见，易被误诊为肺部其他细菌、真菌、结核感染性疾病、肿瘤、血管炎等。PN常发生于全身或肺部局部免疫功能缺陷的宿主，临床症状主要表现为发热、咳嗽、咳痰等，影像学表现包括实变、结节、肿块及空洞等，肺部典型病理损害为坏死性脓肿，慢性感染者形成有肉芽肿，目前尚无特异性的血清学标志物，实验室检查可见外周血白细胞、C反应蛋白等炎症指标升高，低淋巴细胞、低白蛋白血症亦常见。确诊依靠病原学检查，镜下诺卡菌菌体呈多向分枝丝状，可表现为白色、黄色或紫色的粉状或天鹅绒样菌落，细菌培养所需时间较长，易致漏诊，分子技术有助于诊断。治疗上应足量、足疗程、个性化，将药敏试验作为指导。磺胺是主要的治疗药物，联合治疗可作为初始治疗。早期诊断、及时治疗是该病预后的关键。

Pulmonary nocardiosis (PN) is a severe infectious disease caused by Nocardia. It is clinically rare and is easily misdiagnosed as other bacterial, fungal, pulmonary infectious diseases (e.g., tuberculosis), tumors, vasculitis, etc. PN often occurs in hosts with compromised immunity. The symptoms are mainly fever, cough, expectoration, etc. The imaging manifestations include consolidation, nodule, mass, cavity, etc. The typical pathological damage of the lung is necrotic abscess, and granuloma emerges in patients with chronic infection. There are no specific serological markers, hitherto. Laboratory tests show that peripheral blood leukocytes, C-reactive protein, and other inflammatory indicators increase, and low lymphocytes and hypoalbuminemia are also common. The diagnosis relies on etiology. Under the microscope, Nocardia presents multidirectional branching filaments. The colony is white, yellow, or purple, and its surface is powdery or velvety. Culture takes a long time, which is easy to cause missed diagnosis. Molecular techniques are helpful for diagnosis. The treatment should be adequate and individualized, and the drug sensitivity test should be taken as the guidance. Sulfanilamide is the main treatment drug, and combined therapy can be used as the initial treatment. Early diagnosis and timely treatment are the key to the prognosis.