Co-exposure to refractory ceramic fibres and asbestos and risk of pleural mesothelioma

Background:Myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) is occasionally positive in patients with usual interstitial pneumonia (UIP). However, the differences from idiopathic pulmonary fibrosis (UIP/IPF) have not been well reported. Objectives: To clarify the clinical and pathological features of MPO-ANCA-positive UIP. Methods: We retrospectively reviewed the medical records of consecutive MPO-ANCA positive patients with UIP pattern and UIP/IPF patients both diagnosed by surgical lung biopsy in our institution between 2000 and 2012. We compared clinical and pathological characteristics between two groups. Results: Sixteen MPO-ANCA positive UIP and 125 UIP/IPF patients were identified. Median age of 11 men and 5 women was 65 years, and 9 patients had smoking history. Thirteen patients had positive MPO-ANCA at initial visit. During the disease course, positive conversion occurred in 3 patients. Age at surgical biopsy, sex, smoking history, serum level of KL-6, %FVC and %DLCO were not different in two groups. Serum level of CRP was higher in MPO-ANCA positive UIP patients. In pathological analysis, lymph follicles, cellular infiltration in fibrotic areas, and cysts were noted in MPO-ANCA positive UIP patients. Seven patients (43.7%) were complicated with microscopic polyangitis: 3 patients manifested the disease at initial visit, and 4 patients developed during follow-up. The survival time in MPO-ANCA positive UIP was comparable with that of IPF/UIP (64.6 months vs 72.4 months). Conclusions: MPO-ANCA positive UIP was associated with microscopic polyangitis at a high rate, and their prognosis was as poor as that of UIP/IPF.