scholarly journals Pathology of Chronic Hypersensitivity Pneumonitis What Is It? What Are the Diagnostic Criteria? Why Do We Care?

2017 ◽  
Vol 142 (1) ◽  
pp. 109-119 ◽  
Author(s):  
Andrew Churg ◽  
AnaMaria Bilawich ◽  
Joanne L. Wright
Keyword(s):  
Interstitial Pneumonia ◽  
Hypersensitivity Pneumonitis ◽  
Immunosuppressive Agents ◽  
Usual Interstitial Pneumonia ◽  
Clinical Pathology ◽  
Giant Cells ◽  
Survival Prognosis ◽  
Pathologic Features ◽  
Nonspecific Interstitial Pneumonia ◽  
Chronic Hypersensitivity Pneumonitis

Context.— Chronic hypersensitivity pneumonitis (CHP) has emerged from obscurity during the past 15 years and is now recognized as a very common form of fibrosing interstitial pneumonia but one that is frequently misdiagnosed both clinically and on surgical lung biopsy as usual interstitial pneumonia/idiopathic pulmonary fibrosis (UIP/IPF) or fibrotic nonspecific interstitial pneumonia. Objective.— To review the pathologic features of CHP. Data Sources.— Clinical, pathology, and radiology literature were used. Conclusions.— Upper lobe–predominant fibrosis and/or air-trapping on computed tomography scan are features of CHP but not UIP/IPF; however, radiologic separation is possible in only about 50% of cases. Morphologically, CHP sometimes mimics UIP/IPF, but CHP often shows isolated foci of peribronchiolar (centrilobular) fibrosis, frequently associated with fibroblast foci, and in CHP, fibrosis may bridge from the centrilobular region to another bronchiole, an interlobular septum, or the pleura (“bridging fibrosis”). This set of findings is uncommon in UIP/IPF. In addition, CHP may produce a picture of fibrotic nonspecific interstitial pneumonia. Although giant cells/granulomas are usually present in subacute hypersensitivity pneumonitis, they are much less frequently found in CHP, and their absence does not contradict the diagnosis. This diagnostic separation is clinically important because CHP is treated differently than UIP/IPF is (immunosuppressive agents versus antifibrotic agents); further, there are some data to suggest that removing the patient from antigen exposure improves outcome, and there is evidence that patients with CHP have a much better survival prognosis after lung transplantation than do patients with UIP/IPF. In most cases, accurate diagnosis of CHP requires consultation among clinicians, radiologists, and pathologists.

scholarly journals Centrilobular Fibrosis in Fibrotic (Chronic) Hypersensitivity Pneumonitis, Usual Interstitial Pneumonia, and Connective Tissue Disease–Associated Interstitial Lung Disease

2020 ◽  
Vol 144 (12) ◽  
pp. 1509-1516
Author(s):  
Andrew Churg
Keyword(s):  
Interstitial Lung Disease ◽  
Connective Tissue ◽  
Lung Disease ◽  
Interstitial Pneumonia ◽  
Connective Tissue Disease ◽  
Hypersensitivity Pneumonitis ◽  
Interstitial Fibrosis ◽  
Usual Interstitial Pneumonia ◽  
Diffuse Fibrosis ◽  
Chronic Hypersensitivity Pneumonitis

Context.— Various pulmonary diseases can produce centrilobular (peribronchiolar) fibrosis, which may be isolated or associated with other patterns of more diffuse fibrosis. The major forms of interstitial lung disease in which centrilobular fibrosis is found are fibrotic (chronic) hypersensitivity pneumonitis, connective tissue disease–associated interstitial lung disease, and (a disputed issue) usual interstitial pneumonia/idiopathic interstitial fibrosis. Objective.— To review recent literature that addresses separation of these entities. Data Sources.— Data comprised recent publications. Conclusions.— In a specially constructed multidisciplinary discussion exercise, it was found that peribronchiolar metaplasia affecting more than half the bronchioles or more than 2 foci of peribronchiolar metaplasia per square centimeter of biopsy area was strongly associated with a confident diagnosis of fibrotic hypersensitivity pneumonitis. Giant cells or granulomas were only found in cases with a greater than 50% diagnostic confidence in hypersensitivity pneumonitis. Conversely, greater numbers of fibroblast foci per square centimeter and increasing measured amounts of subpleural fibrosis favored a diagnosis of usual interstitial pneumonia. Recent data also suggest that centrilobular fibrosis can be found in usual interstitial pneumonia, although the presence of centrilobular fibrosis statistically favors an alternate diagnosis. Connective tissue disease is a major confounder because many patterns are very similar to fibrotic hypersensitivity pneumonitis or usual interstitial pneumonia. Genetic abnormalities, such as the MUC5B minor allele overlap, in these conditions and at this point cannot be used for discrimination. Thus, the separation of fibrotic hypersensitivity pneumonitis and usual interstitial pneumonia remains a difficult problem. Accurate biopsy diagnosis of all of these diseases requires correlation with imaging and clinical findings, and is crucial for treatment.

Nonspecific Interstitial Pneumonia

Chest Imaging ◽  
2019 ◽  
pp. 459-462
Author(s):  
Cylen Javidan-Nejad
Keyword(s):  
Vascular Disease ◽  
Interstitial Pneumonia ◽  
Drug Toxicity ◽  
Hypersensitivity Pneumonitis ◽  
Usual Interstitial Pneumonia ◽  
Ground Glass Opacity ◽  
Collagen Vascular Disease ◽  
Air Trapping ◽  
Underlying Condition ◽  
Nonspecific Interstitial Pneumonia

Nonspecific interstitial pneumonia (NSIP) represents a less common idiopathic interstitial pneumonia than usual interstitial pneumonia (UIP) with a much better prognosis. Most cases of NSIP are secondary to collagen vascular disease, hypersensitivity or drug toxicity. These secondary forms of NSIP help to explain why it is more often seen on CT than UIP. Unlike UIP, NSIP is characterized by a paucity of honeycombing on CT and greater ground-glass opacity and reticulation. Subpleural sparing when present may suggest the diagnosis. Unlike UIP, NSIP tends to exhibit histologic spatial and temporal homogeneity. When extensive bronchiectasis is seen in association with an NSIP pattern, collagen vascular disease must be considered. When air trapping is encountered, hypersensitivity pneumonitis must be excluded. Biopsy is usually reserved for those patients with an NSIP pattern who do not have a known underlying condition. If the diagnosis of NSIP can be made, immunotherapy may prevent progression and may even reverse some CT findings.

Chronic Hypersensitivity Pneumonitis With a Usual Interstitial Pneumonia-Like Pattern

CHEST Journal ◽  
2016 ◽  
Vol 149 (6) ◽  
pp. 1473-1481 ◽  
Author(s):  
Sahoko Chiba ◽  
Kimitake Tsuchiya ◽  
Takumi Akashi ◽  
Masahiro Ishizuka ◽  
Tsukasa Okamoto ◽  
...  
Keyword(s):  
Interstitial Pneumonia ◽  
Hypersensitivity Pneumonitis ◽  
Usual Interstitial Pneumonia ◽  
Chronic Hypersensitivity Pneumonitis
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