Sharma O P, Fujimura N
University of Southern California School of Medicine, Los Angeles 90033, USA.
Semin Respir Infect. 1995 Jun;10(2):96-106.
Hypersensitivity pneumonitis or extrinsic allergic alveolitis is an immunologically mediated lung disease caused by repeated inhalations of organic antigens. The basic histological lesion consists of a diffuse mononuclear cell infiltration of alveolar wall, alveoli, terminal bronchioles, and neighboring interstitium. The inflammation is often followed by granulomas, which then may progress to fibrosis. Unlike other infectious and noninfectious granulomatous disorders, hypersensitivity pneumonitis is limited to the lung. The disease occurs more frequently in men than in women and children. The acute form of hypersensitivity pneumonitis, characterized by fever, chills, myalgias, cough, and dyspnea, may be confused with acute pneumonitis. Although there is no single radiological, physiological, or immunologic test specific for hypersensitivity pneumonitis, the diagnosis can often be suspected on the basis of a compatible temporal relationship between pulmonary symptoms and a history of environmental or occupational exposure. Once the diagnosis is suspected, the presence of serum precipitating antibodies (immunoglobulin [lg] G), suppressor cytotoxic lymphocytosis in bronchoalveolar lavage (BAL) fluid, and granulomatous alveolitis in lung biopsy specimens is extremely helpful in confirming the diagnosis. For patients in whom the diagnosis is confirmed, avoidance of the causative antigen is the best therapy, although corticosteroids are used to suppress inflammation. Once the fibrosis has developed, the patient may gradually develop respiratory failure or cor pulmonale, possibly resulting in death.
过敏性肺炎或外源性过敏性肺泡炎是一种由反复吸入有机抗原引起的免疫介导性肺部疾病。基本组织学病变包括肺泡壁、肺泡、终末细支气管及邻近间质的弥漫性单核细胞浸润。炎症常继之以肉芽肿形成，随后可能进展为纤维化。与其他感染性和非感染性肉芽肿性疾病不同，过敏性肺炎局限于肺部。该疾病在男性中比在女性和儿童中更常见。过敏性肺炎的急性形式表现为发热、寒战、肌痛、咳嗽和呼吸困难，可能与急性肺炎相混淆。虽然没有单一的影像学、生理学或免疫学检查对过敏性肺炎具有特异性，但根据肺部症状与环境或职业暴露史之间相符的时间关系，通常可怀疑诊断。一旦怀疑诊断，血清沉淀抗体（免疫球蛋白[Ig]G）的存在、支气管肺泡灌洗（BAL）液中的抑制性细胞毒性淋巴细胞增多以及肺活检标本中的肉芽肿性肺泡炎对确诊极为有帮助。对于确诊的患者，避免接触致病抗原是最佳治疗方法，尽管使用皮质类固醇来抑制炎症。一旦发生纤维化，患者可能逐渐发展为呼吸衰竭或肺心病，可能导致死亡。
