Department of Pathology, University of Michigan, Ann Arbor, MI 48109-5054, USA.
Mod Pathol. 2012 Jan;25 Suppl 1:S58-67. doi: 10.1038/modpathol.2011.152.
Hypersensitivity pneumonia is a form of diffuse interstitial lung disease resulting from sensitization to an inhaled antigen. Clinical and radiological features are relatively nonspecific, overlapping significantly with other forms of diffuse interstitial lung disease. Establishing the diagnosis in the absence of lung biopsy is challenging and is heavily dependent on being able to identify a specific antigenic exposure. Lung biopsy is especially important in diagnosing hypersensitivity pneumonia in patients for whom no incriminating exposure has been elucidated. Surgical lung biopsies show a classical combination of findings in the majority of patients, which include an airway-centered, variably cellular chronic interstitial pneumonia, a lymphocyte-rich chronic bronchiolitis, and poorly formed non-necrotizing granulomas distributed mainly within the peribronchiolar interstitium. The bronchiolitis may include variable degrees of peribronchiolar fibrosis and hyperplasia of the bronchiolar epithelium ('peribronchiolar metaplasia'), a characteristic but a nonspecific finding. In some patients, granulomatous inflammation may be lacking, resulting in a histological appearance resembling nonspecific interstitial pneumonia. Late-stage fibrotic hypersensitivity pneumonia results in clinical, radiological, and histological findings that closely mimic usual interstitial pneumonia. The presence of established collagen fibrosis, especially when associated with architectural distortion in the form of honeycomb change, is associated with shorter survivals.
过敏性肺炎是一种弥漫性间质性肺疾病，由对吸入抗原的敏感性引起。临床和影像学特征相对非特异性，与其他形式的弥漫性间质性肺疾病有很大重叠。在没有肺活检的情况下做出诊断具有挑战性，严重依赖于能否识别特定的抗原暴露。对于未能明确致病暴露的患者，肺活检对于诊断过敏性肺炎尤为重要。外科肺活检显示大多数患者存在典型的综合表现，包括以气道为中心的、不同程度细胞性慢性间质性肺炎、富含淋巴细胞的慢性细支气管炎和分布在细支气管周围间质中的不成熟非坏死性肉芽肿。细支气管炎可能包括不同程度的细支气管周围纤维化和细支气管上皮增生（“细支气管周围化生”），这是一种特征性但非特异性的发现。在一些患者中，可能缺乏肉芽肿性炎症，导致组织学表现类似于非特异性间质性肺炎。晚期纤维化性过敏性肺炎导致临床、影像学和组织学表现与寻常型间质性肺炎非常相似。已确定的胶原纤维化的存在，尤其是当与蜂窝状改变形式的结构扭曲相关时，与较短的生存期相关。
