Churg Andrew, Muller Nestor L, Flint Julia, Wright Joanne L
Department of Pathology, University of British Columbia, Vancouver, British Columbia, Canada.
Am J Surg Pathol. 2006 Feb;30(2):201-8. doi: 10.1097/01.pas.0000184806.38037.3c.
Hypersensitivity pneumonitis (HP) is traditionally divided on clinical grounds into acute, subacute, and chronic stages. Most biopsy specimens come from patients in the subacute stage, in which there is a relatively mild, usually peribronchiolar, chronic interstitial inflammatory infiltrate, accompanied in most cases by poorly formed interstitial granulomas or isolated giant cells. However, the pathologic features in the chronic, ie, fibrotic stage, are poorly defined in the literature. These features are important to recognize because the chronic stage of HP is often associated with a poor prognosis. We reviewed 13 cases of chronic HP. Where information was available, exposures to the sensitizing agent had generally occurred over a long period of time. Three patterns of fibrosis were seen: 1) predominantly peripheral fibrosis in a patchy pattern with architectural distortion and fibroblast foci resembling, microscopically, usual interstitial pneumonia (UIP); 2) relatively homogeneous linear fibrosis resembling fibrotic nonspecific interstitial pneumonia (NSIP); and 3) irregular predominantly peribronchiolar fibrosis. In some instances, mixtures of the UIP-like and peribronchiolar patterns were found. In all cases, the presence of scattered poorly formed granulomas, or isolated interstitial giant cells, or sometimes only Schaumann bodies indicated the correct diagnosis. In 7 cases, areas of typical subacute HP were present as well. High-resolution CT scans showed variable patterns ranging from severe fibrosis, in some instances with an upper zone predominance, to predominantly ground glass opacities with peripheral reticulation. We conclude that, at the level of morphology, chronic HP may closely mimic UIP or fibrotic NSIP. If no areas of subacute HP are evident, the presence of isolated giant cells, poorly formed granulomas, or Schaumann bodies is crucial to arriving at the correct diagnosis, and the finding of peribronchiolar fibrosis may be helpful. Despite the presence of extensive fibrosis, some patients responded to removal from exposure and steroid therapy.
传统上，根据临床情况，超敏性肺炎（HP）可分为急性、亚急性和慢性阶段。大多数活检标本来自亚急性期患者，此阶段存在相对较轻的、通常为细支气管周围的慢性间质性炎症浸润，多数情况下伴有形成不良的间质性肉芽肿或孤立的巨细胞。然而，关于慢性（即纤维化阶段）HP的病理特征，文献中描述较少。认识这些特征很重要，因为HP的慢性阶段通常预后较差。我们回顾了13例慢性HP病例。在可获取信息的情况下，接触致敏原通常发生在较长时间段内。观察到三种纤维化模式：1）以斑片状为主的周边纤维化，伴有结构扭曲和成纤维细胞灶，在显微镜下类似于普通间质性肺炎（UIP）；2）相对均匀的线性纤维化类似于纤维化非特异性间质性肺炎（NSIP）；3）不规则的、以细支气管周围为主的纤维化。在某些情况下，发现了UIP样模式和细支气管周围模式的混合。在所有病例中，散在的形成不良的肉芽肿、孤立的间质性巨细胞或有时仅沙曼小体的存在提示了正确的诊断。7例病例中还存在典型的亚急性HP区域。高分辨率CT扫描显示了多种模式，从某些情况下以上叶为主的严重纤维化到以磨玻璃影为主并伴有周边网状影。我们得出结论，在形态学层面，慢性HP可能与UIP或纤维化NSIP极为相似。如果没有明显的亚急性HP区域，孤立巨细胞、形成不良的肉芽肿或沙曼小体的存在对于做出正确诊断至关重要，细支气管周围纤维化的发现可能也有帮助。尽管存在广泛纤维化，但一些患者脱离接触并接受类固醇治疗后有反应。
