Background/Purpose:

Rarely, ANCA-positive vasculitis patients are found to have interstitial lung disease (ILD). Clinical characteristics and prognosis are not well known in these patients. The largest report to date is from Japan, describing microscopic polyangitis (MPA) as the most common type of ANCA vasculitis associated to ILD.

Methods:

We retrospectively reviewed 26 patients at Mayo Clinic Florida for the past 10 years diagnosed with both ANCA-positive vasculitis and ILD (AAV-ILD). We compared the clinical characteristics of AAV-ILD to idiopathic pulmonary fibrosis (IPF) and idiopathic pneumonia with autoimmune features (IPAF) patients

Results:

There were 24 AAV patients. 11 were male and 13 were female. 14 patients had microscopic polyangitis (MPA), 8 patients had granulomatosis polyangitis (GPA), and 2 patients had eosinophilic granulomatosis polyangitis (EGPA). Usual interstitial pneumonia (UIP) pattern was found in 11 patients and other patterns were inconsistent with UIP.

P-ANCA and anti-MPO were positive in most MPA patients and c-ANCA and anti-proteinase-3 were positive in most GPA patients. Cyclophosphamide and corticosteroids were the mainstay of therapy, and rituximab was used in 13 patients. A total of 5 patients died. Death was directly related to the progression of ILD in 4 patients.

Conclusion:

We were able to identify the characteristics of ILD in ANCA-positive vasculitis patients. We observed that a fair number of PR3-positive/GPA patients do have ILD, comparable to MPA. This is to our knowledge the largest case series of clinically confirmed ANCA vasculitis with ILD reported in North America.

Table 1.  Comparison  between AAV-ILD, Idiopathic pulmonary fibrosis (IPF), and idiopathic pneumonia with autoimmune features (IPAF)

AAV-ILD, ANCA-associated vasculitis with interstitial lung disease; DLCO, diffusing capacity; Data are given as median (minimum, maximum) for numeric variables and number (percent) for categorical variables.  P values result from the nonparametric Kruskal-Wallis test for numeric variables and the Fisher exact test for categorical variables.  Pairwise comparisons were performed when the P value was less than 0.05; superscripts a and b are given to indicate pairwise differences (P<0.05) where groups without a common superscript were considered to have a statistically significant difference.