Transbronchial Cryobiopsy in the Diagnosis of Diffuse Lung Disease

Multidisciplinary Approach to the Diagnosis of Idiopathic Interstitial Pneumonias: Focus on the Pathologist's Key Role

Idiopathic Interstitial Pneumonias (IIPs) are a heterogeneous group of the broader category of Interstitial Lung Diseases (ILDs), pathologically characterized by the distortion of lung parenchyma by interstitial inflammation and/or fibrosis. The American Thoracic Society (ATS)/European Respiratory Society (ERS) international multidisciplinary consensus classification of the IIPs was published in 2002 and then updated in 2013, with the authors emphasizing the need for a multidisciplinary approach to the diagnosis of IIPs. The histological evaluation of IIPs is challenging, and different types of IIPs are classically associated with specific histopathological patterns. However, morphological overlaps can be observed, and the same histopathological features can be seen in totally different clinical settings. Therefore, the pathologist's aim is to recognize the pathologic-morphologic pattern of disease in this clinical setting, and only after multi-disciplinary evaluation, if there is concordance between clinical and radiological findings, a definitive diagnosis of specific IIP can be established, allowing the optimal clinical-therapeutic management of the patient.

Incidental discovery of interstitial lung disease: diagnostic approach, surveillance and perspectives

The incidental discovery of pre-clinical interstitial lung disease (ILD) has led to the designation of interstitial lung abnormalities (ILA), a radiological entity defined as the incidental finding of computed tomography (CT) abnormalities affecting more than 5% of any lung zone. Two recent documents have redefined the borders of this entity and made the recommendation to monitor patients with ILA at risk of progression. In this narrative review, we will focus on some of the limits of the current approach, underlying the potential for progression to full-blown ILD of some patients with ILA and the numerous links between subpleural fibrotic ILA and idiopathic pulmonary fibrosis (IPF). Considering the large prevalence of ILA in the general population (7%), restricting monitoring only to cases considered at risk of progression appears a reasonable approach. However, this suggestion should not prevent pulmonary physicians from pursuing an early diagnosis of ILD and timely treatment where appropriate. In cases of suspected ILD, whether found incidentally or not, the pulmonary physician is still required to make a correct ILD diagnosis according to current guidelines, and eventually treat the patient accordingly.

In patients with interstitial lung abnormalities (ILA), monitoring of those at risk of progression is currently recommended, and pulmonary physicians should pursue an early diagnosis when ILA become clinically significant to facilitate timely treatment https://bit.ly/3HKOQc8

Comparison between Image-Guided Transbronchial Cryobiopsies and Thoracoscopic Lung Biopsies in Canine Cadaver: A Pilot Study

Simple Summary

A definitive diagnosis for most pulmonary diseases is possible only through histopathological examination. The literature describes different methods of lung biopsy sampling depending on the case. However, for the diagnosis of diffuse interstitial pulmonary diseases and some peripheral neoplasms, the gold standard is represented by surgical lung biopsies. Given their invasiveness and the high percentage of risk for the patient, in most cases they are not carried out, resulting in a serious diagnostic gap. In human medicine, transbronchial lung cryobiopsies have been introduced as an alternative, which have shown high efficacy and reduced invasiveness. This study aims to evaluate the feasibility of the new technique in dogs by subjecting dog cadavers to pulmonary cryobiopsy and surgical lung biopsies, and to compare the samples obtained for histopathological quality. In total, 42 tissue samples were compared. Pulmonary cryobiopsies were smaller than surgical biopsies but with high levels of agreement upon histological evaluation. This study demonstrates the feasibility of the technique in dogs and the collection of specimens with size and histological features comparable to those from surgical biopsies.

Abstract

To date, the only method of sampling lung tissue with a high diagnostic yield is represented by surgical lung biopsies (SLB), which are highly invasive and have a high risk/benefit ratio. In humans, transbronchial lung cryobiopsies (TBLC) have recently been introduced, which are described to be less invasive and able to significantly increase diagnostic confidence in most patients with interstitial lung diseases. The aim of this study was to evaluate the feasibility and diagnostic yield of TBLC compared to SLB in small animals. A total of 21 pulmonary cryobiopsies under fluoroscopic and real-time CT fluoroscopic guidance and 21 video-assisted thoracoscopic surgery (VATS) lung biopsies were collected from three dog cadavers. Upon histological examination, cryobiopsy samples were smaller than VATS biopsies, but were still large enough to reach a specific diagnosis or to allow pattern recognition. Morphological features on TBLC and SLB were concordant in all cases. Cryobiopsy samples showed fewer artifacts and a higher percentage of alveolar tissue than VATS samples. TBLC is a feasible and useful alternative to SLB for lung histopathological examination in dogs. The effectiveness and reduced invasiveness of TBLC compared to SLB could represent many advantages in the diagnosis of diffuse lung diseases in small animals.

Diagnosis of Hypersensitivity Pneumonitis: Review and Summary of American College of Chest Physicians Statement

Assessment of lung biopsies for the diagnosis of hypersensitivity pneumonitis (HP) is one of the most difficult diagnostic problems for surgical pathologists. It is a form of interstitial lung disease resulting from an immune reaction provoked by an inhaled antigen in susceptible individuals. Although this definition sounds simple, in practice, the diagnosis of HP can be challenging. To address these issues, the American College of Chest Physicians (CHEST) has recently published a guideline for the diagnosis of HP. In this review, we will explore the multidisciplinary diagnostic evaluation of HP with a focus on the pathologic features as outlined in the CHEST guidelines. The histologic criteria are divided into 4 diagnostic categories: (1) Typical nonfibrotic HP or fibrotic HP; (2) Compatible with nonfibrotic HP or fibrotic HP; (3) Indeterminate for nonfibrotic or fibrotic HP; and (4) Alternative Diagnosis. It is important to emphasize that patterns 1 to 3 do not represent discrete histologic entities or pathologic diagnoses. Rather, these categories are meant to serve as a practical guide for organizing a complex set of overlapping histologic patterns into an integrated diagnostic framework for facilitating multidisciplinary discussion. High-resolution computed tomography features are also summarized, emphasizing how the correlation of lung biopsies with computed tomography findings can help to favor the diagnosis, particularly in cases where biopsies are not typical for HP. This review highlights details of the histologic spectrum of HP as well as the utility of different types of biopsies and bronchoalveolar lavage. We also emphasize the importance of multidisciplinary discussion and the complex differential diagnosis.

Hypersensitivity pneumonitis: new concepts and classifications

The clinical and pathologic diagnosis of hypersensitivity pneumonitis has been confounded by conflicting definitions, with two recent guidelines suggesting that hypersensitivity pneumonitis simply be diagnosed as nonfibrotic or fibrotic. Nonfibrotic hypersensitivity pneumonitis is usually characterized by a bronchiolocentric chronic interstitial inflammatory infiltrate, frequently but by no means always with associated granulomas or giant cells. Fibrotic hypersensitivity pneumonitis may take the form of interstitial fibrosis confined to the peribronchiolar regions, or fibrotic nonspecific interstitial pneumonia, or a process similar to and sometimes indistinguishable from usual interstitial pneumonia/idiopathic interstitial fibrosis, but the exact pathologic features that favor a diagnosis of fibrotic hypersensitivity pneumonitis are disputed. Granulomas/giant cells are much less frequent in fibrotic compared to nonfibrotic hypersensitivity pneumonitis. Extensive peribronchiolar metaplasia, particularly peribronchiolar metaplasia affecting more than half the bronchioles, supports a diagnosis of fibrotic hypersensitivity pneumonitis over usual interstitial pneumonia, as does the presence of predominantly peribronchiolar disease with relative subpleural sparing. Clinical and CT features are crucial to the diagnosis of hypersensitivity pneumonitis: sparing of the lung bases, centrilobular nodules, air-trapping, or the triple density sign with fibrosis favor a diagnosis of fibrotic hypersensitivity pneumonitis. At this point there are no molecular tests that reliably separate fibrotic hypersensitivity pneumonitis from other forms of interstitial lung disease. Currently the separation of fibrotic hypersensitivity pneumonitis from usual interstitial pneumonia is crucial to treatment (immunosuppressives for the former, anti-fibrotics for the latter) but this approach is changing and all progressive fibrosing interstitial pneumonias will probably be treated with antifibrotics in the future.

Evaluation of Transbronchial Lung Cryobiopsy Freezing Time, Biopsy Size, Histological Quality, and Incidence of Complication: A Prospective Clinical Trial

BACKGROUND

Transbronchial cryobiopsy (TBCB), a novel way of obtaining a specimen of lung tissue using a flexible cryoprobe, can obtain large lung biopsies without crush artifacts. The freezing time of TBCB was empirically selected from 3 to 7 s in the previous studies. However, no consensus has yet been reached regarding the optimal freezing time used in TBCB.

OBJECTIVES

The primary endpoint was biopsy size in different freezing times. The secondary endpoints included sample histological quality, diagnostic confidence, and complications in different freezing times.

METHODS

Patients who were suspected of DPLD requiring histopathological examination for further evaluation were enrolled in this study. Distinct biopsies were obtained by using different freezing times increased from 3 to 6 s sequentially. Samples were reviewed by 2 external expert pathologists.

RESULTS

A total of 33 patients were enrolled, and 143 transbronchial cryobiopsies were taken in this trial. An average of 4.33 samples were taken from each patient. The mean biopsy size of different freezing times from 3 to 6 s was 9.10 ± 4.37, 13.23 ± 5.83, 16.26 ± 5.67, and 18.83 ± 7.50 mm2, respectively. A strong correlation between freezing time and biopsy size was observed (r = 0.99, p < 0.01). Statistically significant difference of biopsy size was detected in the freezing time of 3 s versus 4 s (p < 0.01) and 4 s versus 5 s (p = 0.02), but not in the freezing time of 5 s versus 6 s (p = 0.10). Overall bleeding in different freezing times from 3 to 6 s was 53.33%, 67.50%, 89.47%, and 77.14%, respectively. A significantly higher overall bleeding was observed when the freezing time exceeded 4 s (RR = 1.67, p < 0.01). Pneumothorax occurred in 4 cases (12.12%). One lethal case (3.03%) was noted 25 days after TBCB. Lung parenchyma was preserved well in all cryobiopsy samples. Thirty-one (93.94%) patients' histopathological findings were identified as sufficient to establish a CRP diagnosis. There was no statistical difference in diagnostic confidence between different freezing times.

CONCLUSION

A longer freezing time was associated with a larger size of the biopsy sample but a higher risk of bleeding. The optimal transbronchial cryobiopsy freezing time is 3-4 s, which is easily achievable and provides an adequate biopsy size whilst creating a safety threshold from complications.

Flexible Bronchoscopy Biopsy Tools and Techniques to Optimize Diagnostic Yield: A Contemporary Review

Background:

Flexible bronchoscopy is essential in diagnosing many pathologic conditions, and tools such as lavage and biopsies using brushes, forceps, and needles are paramount to success.

Introduction:

Bronchoscopists worldwide are routinely confronted with questions about such tools regarding the type, size, utility, costs, safety, anticipated yield, and others. Does the underlying suspected condition matter to the choice of instruments used? What is the anticipated outcome for benign versus malignant diseases? These and other questions are raised daily by bronchoscopists.

Methods:

Pubmed was reviewed for research in the English language pertaining to diagnostic bronchoscopy. The literature is conflicting on the benefits of the types of tools available. The success of brush biopsies, forceps, and transbronchial needle aspiration is only partially dependent on the size of the instrument used or its other characteristics. Multiple biopsies are needed, and different approaches may be complementary in some circumstances.

Results:

By understanding the factors that involve in a biopsy, the bronchoscopist is more likely to be successful when a crucial diagnosis is mandatory.

Conclusion:

This review aims to be a reference to bronchoscopists everywhere as they contemplate their approach to flexible diagnostic bronchoscopy.