Should we perform surgical lung biopsy when transbronchial cryobiopsy provides unclassifiable interstitial pneumonitis in a patient with diffuse interstitial lung disease

Aim: Transbronchial cryobiopsy(TBC) is a new technique in obtaining large tissue samples in diffuse interstitial lung disease(DILD) with high diagnostic yield comparable to surgical lung biopsy(SLB). Yet, the exact role of SLB in pathologic diagnosis(DX) of DILD is unclear when TBC provides no definite diagnosis. We evaluated the rate of definite DX by SLB when TBC was not diagnostic in DILD patients. Method: Consecutive consenting DILD patients(n=26) underwent TBC. An individual experienced lung pathologist(ELP) examined all the specimens. Pattern-based histopathological approach was used in examining the samples. If analysis of TBC specimens showed unclassifiable DILD, the cases would be reviewed at multidisciplinary discussion(MD) including clinicians, radiologists, and a different EPL.MD diagnosis(MDD) was recorded for each case. Then they underwent SLB. The primary outcome was diagnostic yield of SLB in unclassifiable DILD by TBC. The secondary outcome was agreement of MD diagnosis and SLB pathologic diagnosis. Result:26 patients (male=18, age:48±12yrs) were enrolled. TBC reached the specific diagnosis in 73%patients (n= 19). In the remaining, pathologic exam showed indeterminate pattern of fibrosis and cellular infiltrates; unclassifiable DILD (27%).In the 7 with non-diagnostic TBC, SLB reclassified only 3 to definite diagnoses (43%).There was high agreement between SLB diagnosis and MDD in these 3 (100%). In the remaining(n=4), SLB was non-diagnostic and didn’t reclassify to alternative diagnosis rather than MDD. Conclusion: In case of unclassifiable DILD by TBC, MD might be more helpful than SLB.