# Interstitial Lung Disease as a Herald of P-ANCA Vasculitis: A Case of Evolving Multisystem Disease

## TL;DR

A 72-year-old man with lung disease was later diagnosed with vasculitis after persistent symptoms and atypical test results.

## Contribution

Highlights diagnostic challenges of AAV when overlapping with PMR and interstitial lung disease.

## Key findings

- Persistent symptoms and atypical MRI findings led to biopsies confirming AAV.
- Patient developed diffuse alveolar hemorrhage requiring intubation, which improved with treatment.
- AAV diagnosis was complicated by overlapping PMR-like symptoms and underlying lung disease.

## Abstract

We present the case of a 72-year-old man with idiopathic pulmonary fibrosis (IPF) who presented with stiffness and pelvic girdle pain and was initially treated for polymyalgia rheumatica (PMR). Despite transient improvement on steroids, persistent symptoms and atypical MRI findings led to muscle and renal biopsies, revealing necrotizing vasculitis and pauci-immune glomerulonephritis. Positive myeloperoxidase and perinuclear antineutrophil cytoplasmic antibody titers confirmed the diagnosis of antineutrophil cytoplasmic antibody-associated vasculitis (AAV). The patient's course was complicated by diffuse alveolar hemorrhage requiring intubation, which improved with pulse steroids and cyclophosphamide. The patient stabilized on methotrexate and methylprednisolone. This case highlights the complexity of diagnosing AAV, especially with overlapping PMR-like symptoms and underlying interstitial lung disease.