Idiopathic pulmonary fibrosis and p-ANCA positivity predating manifestations of systemic vasculitis

The occurrence of perinuclear anti-neutrophilic cytoplasmic antibodies (p-ANCA) in pulmonary fibrosis has been reported in a number of small studies, however, the appearance of p-ANCA in already established idiopathic pulmonary fibrosis (IPF), predating the manifestations of vasculitis has not been widely appreciated. We report 2 cases with radiographic evidence of established IPF where p-ANCA was negative at the time of diagnosis and became positive during the course of the disease, for a variable period of time, prior to the subsequent development of systemic vasculitis. Our cases suggest a possible rationale for serial p-ANCA measurements in patients with pulmonary fibrosis even in the absence of features suggestive of vasculitis. Furthermore, the required frequency of ANCA measurement in the absence of clinical features of vasculitis is unknown. Larger studies with repetitive p-ANCA measurement in tandem with ongoing clinical assessment for vasculitis are required to assess the prevalence of ANCA and to confirm our observation.