Pulmonary amyloidosis diagnosed via transbronchial lung cryobiopsy without surgical lung biopsy: A case series.

Pulmonary amyloidosis is a rare disease characterized by abnormal extracellular deposition of amyloid fibril in the lung tissue, and the identification of amyloid deposits is essential for its diagnosis. Surgical lung biopsy (SLB) is a standard diagnostic method for pulmonary amyloidosis. However, it has a relatively high post-procedural mortality rate. Recently, transbronchial lung cryobiopsy (TBLC) has been gradually used for diagnosing interstitial lung disease. However, its diagnostic efficacy for pulmonary amyloidosis has not yet been validated. Here, we describe two cases of pulmonary amyloidosis with deposition of amyloid light chain detected via TBLC. Since SLB is a high-risk procedure for the patients due to age and complications, TBLC was performed. Both patients presented with Congo red-positive amyloid deposits. One patient with localized pulmonary amyloidosis had a good clinical course without therapeutic intervention and was followed up. The other with systemic amyloidosis received chemotherapy and presented with a stable clinical course. TBLC can collect a larger pulmonary specimen for pulmonary amyloidosis than forceps biopsy and has fewer complications and a lower mortality rate than SLB. Thus, it can be a diagnostic method for pulmonary amyloidosis.