Background/Purpose: Anca-associated vasculitis (AAV) is characterized by vascular inflammation in multiple organs. The diagnosis can be made clinically using a number of different criteria. The lungs are commonly affected, with a broad range of manifestations described including cough, dyspnea, respiratory failure, and pulmonary hemorrhage. Multiple pulmonary histopathologic patterns have been described in AAV, which requires invasive tissue sampling through lung biopsy and is not without risk. Here, we have reviewed the histopathologic findings in a series of pediatric AAV, and discuss procedural outcomes and yield of lung biopsies in this population.

Methods: After IRB approval, we performed a retrospective chart review of all patients < 18 years of age presenting to our institution with a diagnosis of AAV who underwent lung biopsy. We reviewed histopathologic features, serologies, timing of biopsy, and complications.

Results: 14 patients met inclusion criteria, 9 patients with a diagnosis of microscopic polyangiitis (MPA), and 5 patients with granulomatosis with polyangiitis (GPA). 10/14 (71%) of the biopsies were performed between 2009 and 2013, and only 4 (29%) from 2015 to present. 13/14 patients required initial admission on presentation for respiratory symptoms. 11/14 required respiratory support. All patients had abnormal chest imaging at presentation. 11/14 had concerns for pulmonary hemorrhage. All 5 patients with GPA had an elevated serine protease-3 (PR3). Mean PR3 level was 703 AU/mL (range 49-1353 AU/mL). Myeloperoxidase (MPO) was elevated in all MPA patients. Mean MPO level was 109 AU/mL (range 24-186 AU/mL). The indication for biopsy was to confirm the diagnosis prior to initiating therapy in 11 patients (78%), as part of an infectious work-up in 2 (14%), and as part of an interstitial lung disease work-up in 1 (7%).  9/14 (64%) biopsies had findings consistent with a diagnosis of AAV, 4/9 (44%) of the MPA patients compared to 5/5 (100%) of the GPA patients. The most common findings on histopathology in GPA patients were vasculitis (100%), granulomatous changes (20%), and alveolar hemorrhage (60%). Only 44% of MPA patients had signs of vasculitis, but 100% showed signs of alveolar hemorrhage. The main post-procedure complication was pneumothorax, in 28% of patients.

Conclusion: We found that lung biopsy had a higher diagnostic yield in GPA compared to MPA. On histology, confirmation of vasculitis and pulmonary hemorrhage were the most common findings. In our cohort, the diagnosis of AAV was able to be made with clinical features and a positive serology in all cases. Therefore, considering the risks associated with obtaining a lung biopsy, they should not be routine and reserved for uncertain cases.

« Back to ACR Convergence 2020

ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-role-of-lung-biopsy-in-pediatric-anca-associated-vasculitis/