Updates in Diagnostic Tools for ILD

Interstitial lung disease (ILD) is a group of diffuse parenchymal disorders, which are diagnosed in many cases by multidisciplinary discussion (MDD). In some cases, diagnosis can be challenging, and the addition of histopathology can increase diagnostic confidence. The tools to obtain a histopathological sample to diagnose ILD are expanding. In this review, we will discuss the various modalities, their sensitivities and specificities, and procedural complication rates. In this review, we conducted a comprehensive review of literature focusing on emerging and established diagnostic tools for ILD. A systematic search of peer-reviewed publications was performed using PubMed with a focus on clinical trials, retrospective and prospective cohort studies, and systematic reviews. The key diagnostic modalities in focus were genomic classifier (GC), transbronchial cryobiopsy (TBLC), surgical lung biopsy (SLB), endobronchial ultrasound cryobiopsy (EBUS-C), genetic testing, and speckled transthoracic echocardiography (STE). Data extracted from these studies focused on diagnostic yield, specificity, sensitivity, and procedural complication rate. Genomic classifier, a gene-based molecular diagnostic tool, has a high specificity for histological usual interstitial pneumonia (UIP). However, in cases of a negative result, it often results in a need for further invasive sampling by TBLC or SLB. TBLC results in a larger histological sample, which can increase diagnostic yield and increase diagnostic confidence at MDD. Recent prospective trials have compared this modality with SLB and found 63-77% interobserver agreement between pathologists. SLB remains the gold standard with diagnostic yields reported to be more than 90%. EBUS-C has shown promising results increasing diagnostic yield in patients with suspected sarcoidosis or lymphoma. All diagnostic modalities have procedural complications with most common being pneumothorax, bleeding and, rarely, death. Advancements in diagnostic tools for interstitial lung disease (ILD) have significantly improved accuracy. Even though surgical lung biopsy remains the gold standard, the alternative modalities are promising and provide a promising yield with a lower procedural risk.