Steinack, C., Gaspert, A., Rüschoff, J., Gautschi, F., Hage, R., Schuurmans, M., and Franzen, D.
Acute cellular rejection (ACR) is a frequent complication within the first year after lung transplantation (LTx) and an important risk factor for chronic lung allograft dysfunction (CLAD) and mortality. The revised classification for the standardization of nomenclature in the diagnosis of allograft rejection of 2007 was based on histologic findings using transbronchial forceps biopsy (TBFB). However, its diagnostic accuracy (DA) is limited due to the small sample size and crush artifacts. Transbronchial lung cryobiopsy (TBLC) is a technique for diagnosis of interstitial lung diseases with improved DA compared to TBFB, but with insufficient evidence in diagnosis and screening of ACR. This study aims to provide data on safety, diagnostic utility and impact on treatment decisions after TBLC in lung transplant recipients (LTRs). Between December 2019 and June 2020, both TBFB and LBLC were obtained serially in LTRs during the same bronchoscopy session to detect ACR. According to our protocol, after 5 TBFB samples, 2 samples by TBLC were taken from different lung segments. The biopsies were scored according to the recent ISHLT criteria by a dedicated transplant pathologist, assessing TBFB and TBLC samples independently. The severity of bleeding we assessed with the Nashville Bleeding Scale (grade 1 - 4), and pneumothoraces were excluded with routine chest radiography. Totally, 25 consecutive procedures in 17 LTRs (13 males, median age 58) were performed either as routine surveillance bronchchoscopy (n = 19) or as clinically indicated (n = 6) using flexible bronchoscopy. Retrospective analysis of 125 TBFB and 50 TBLC samples was performed. ACR (A1 - A3) was detected in 6 cases (24%) by TBLC resulting in a change of immunosuppressive strategy, compared to 0% by TBFB. Non-diagnostic biopsy samples were noted in 3 cases (12%) of TBLC compared to 21 (84%) of TBFB. The biopsy procedure was complicated by moderate (grade 2) bleeding in 6 (24%) cases as a complication of TBCB, since it occurs immediately after this procedure. No pneumothorax was detected. TBLC provided improved DA for diagnosis of ACR with an acceptable safety profile, leading to reclassification and a change of treatment strategy in 24% of the cases. Further prospective studies are needed to confirm these findings and recommend TBLC as gold standard to detect ACR. [ABSTRACT FROM AUTHOR]