TY - JOUR T1 - Interstitial pneumonia with autoimmune features: a new classification still on the move JF - European Respiratory Review JO - EUROPEAN RESPIRATORY REVIEW DO - 10.1183/16000617.0047-2018 VL - 27 IS - 148 SP - 180047 AU - Lorenzo Cavagna AU - Miguel A. Gonzalez Gay AU - Yannick Allanore AU - Marco Matucci-Cerinic Y1 - 2018/06/30 UR - http://err.ersjournals.com/content/27/148/180047.abstract N2 - In the past decade, the attention has been focused on the relationship between interstitial lung disease (ILD) and connective tissue diseases (CTDs). The clinical impact, as well as the therapeutic approach, classification and diagnosis have been addressed. These two latter items represent an area of great interest because the underlying conditions leading to ILD and the most appropriate treatment still needs to be defined. Recently, the European Respiratory Society/American Thoracic Society proposed the interstitial pneumonia with autoimmune features (IPAF) criteria which represents the effort of pulmonologists to classify patients that may remain clinically undefined [1]. The analysis of these criteria shows that IPAF, similarly to pulmonary arterial hypertension classification [2], may cluster conditions referring to a wide spectrum of rheumatic conditions such as systemic sclerosis, myositis, rheumatoid arthritis and overlap syndromes. These diseases are characterised by highly different characteristics, evolution and therapeutic approaches. Furthermore, IPAF criteria have an intrinsically changing structure, related to the regular update of existing CTD classification criteria and to the even more common identification of new biomarkers in CTDs. By far the most important effect of these criteria is the identification of a grey zone of not well-defined rheumatology conditions, e.g. anti-synthetase syndrome (ASSD) [3]. In this issue of the European Respiratory Review, Sambataro et al. [4] address the need to identify specific clinical characteristics and potential areas of improvement in IPAF patients. The starting point of the review is interesting because of the exclusion of papers that included patients diagnosed with ASSD, because no ASSD established classification criteria still exist. The authors' choice is related to the unique characteristics of ASSD, in which it is not unusual to observe the occurrence during follow-up of findings lacking at disease onset. [5]. However, as reported previously [6], in the case of anti-synthetase antibody positivity, the diagnostic scenario may vary with the same patient diagnosed with ASSD if referred to a rheumatologist, or IPAF if referred to a pulmonologist. In fact, a high prevalence of anti-synthetase antibody positivity is reported in the majority of papers evaluated by Sambataro et al. [4], thus confirming the fact that despite the presence of this antibody (identifying ASSD) patients may frequently end up being classified as having IPAF. However, some IPAF patients could not be tested for the entire spectrum of antibodies, probably due to the local unavailability of these tests, or because initial anti-Ro antibody positivity might have prompted the clinicians to evaluate further non-anti-Jo-1 myositis specific auto-antibodies. In fact, it is established that anti-Ro antibodies and anti-synthetase antibodies may co-occur in about 50% of cases, even when patients could be classified as IPAF [7]. Furthermore, we should also consider that if eight anti-synthetase antibodies have been identified to date, at least another 12 aminoacyl-tRNA synthetase enzymes exist, and that the entire spectrum of anti-synthetase antibodies is not covered by any of the existing commercially available tests. All these points clearly indicate the risk that anti-synthetase antibody positivity could be underestimated and that it could be clustered in IPAF. This evidence clearly suggests that well-established and clinically based ASSD classification criteria are needed to reduce the risk of stratifying patients across specialties, in areas that may contribute to real-time incorrectly diagnosed primary disease. Recently, the CLASS (classification criteria of anti-synthetase syndrome) project has been funded by the American College of Rheumatology and the European League against Rheumatism. The aim of the project is to define clinically based criteria of ASSD involving a large number of rheumatology, pulmonology, dermatology, immunology and internal medicine centres expert in the management of rheumatoid arthritis, systemic sclerosis, Sjogren's syndrome and other lung fibrosing conditions. From a scientific point of view, by putting together different specialists we hope to solve the daily discussions about “anti-synthetase antibody positive patient classification” that may delay the correct approach and treatment of affected patients.IPAF classification criteria include several autoimmune conditions with different evolution. The progression into established CTD is common and a continuous up-to-date process of classification criteria of both IPAF and CTD is mandatory. http://ow.ly/pXNW30knUzl ER -