Airway Biopsy Results From Patients With Suspected Granulomatosis With Polyangiitis (2005-2015): Clinicopathological Correlation and Proposal of an Algorithm to Improve Diagnosis.

Objectives: The aim of this study was to review the histologic diagnostic yield of airway biopsies with a suspected granulomatosis with polyangiitis (GPA) diagnosis at a single center devoted to respiratory diseases using previously published criteria. A secondary aim was to apply the algorithm proposed by the European Medicines Agency to determine whether more biopsies were confidently identified as having GPA diagnoses.

Methods: From a total of 132 airway biopsies (2005-2015), 50 were randomly selected for second review by an expert pathologist, and previously published criteria were applied. Thereafter, antineutrophil cytoplasm autoantibody testing results and the European Medicines Agency algorithm were applied.

Results: Repeat review and application of the published criteria resulted in an increase from 16 to 25 diagnoses of GPA. This increased to 35 of 50 when antineutrophil cytoplasm autoantibody results and the European Medicines Agency algorithm were applied. Interobserver correlation was 57.5% among pathologists (κ = 0.19), which was likely due to missing clinical information and inadequate tissue samples. Patients with generalized disease were 2.6 times more likely to obtain diagnostic GPA airway biopsy results than those with limited disease (airway only).

Conclusions: An increase in the diagnostic yield of this malady could be attained by following an algorithm that incorporates carefully retrieved clinical, endoscopic, and serologic data, coupled with systematic histopathologic sample review.