PRTN3 and systemic sclerosis: In contrast with MSA and SSc-specific antibodies, the interpretation of positive RF, anti-Ro antibodies or low titers of anti-dsDNA and ACPA in patients with a pulmonary-dominant condition is challenging and performance of a surgical lung biopsy at the beginning of the disease -particularly in patients showing UIP radiographic patterns–might be a good choice both to correctly characterize the disease but also to better understand pathophysiological processes involved.