Idiopathic Interstitial Pneumonias with Connective Tissue Diseases Features: A Review

A systematic approach is recommended to search for clinical and biological features of connective tissue disease (CTD) in any patient with interstitial lung disease (ILD). In the diagnostic approach to ILD, a diagnosis of CTD should be considered particularly in women and subjects younger than 50 years, and in those with an imaging and/or pathological pattern of non-specific interstitial pneumonia. However, the diagnosis of CTD may be difficult when ILD is the presenting or the dominant manifestation of CTD. A proportion of patients with ILD present symptoms that belong to the spectrum of CTD and/or biological autoimmune features, but do not fulfil diagnostic criteria for a given CTD. Some imaging and histopathological patterns may also suggest the presence of an underlying CTD. Although studies published to date used heterogeneous definitions and terminology for this condition, evidence is accumulating that even limited CTD features are relevant regarding symptoms, imaging features, pathological pattern and possibly evolution to overt CTD, whereas the impact on prognosis needs confirmation. Conversely, autoantibodies alone do not seem to impact the prognosis or management in patients with otherwise typical idiopathic pulmonary fibrosis and no extra-pulmonary manifestation. A collective international multidisciplinary effort has proposed a uniform definition and criteria for 'interstitial pneumonia with autoimmune features', a condition characterized by limited CTD features occurring in the setting of ILD, with the aim of fostering future clinical studies. Referral of ILD patients suspect to have CTD to a rheumatologist and possibly multidisciplinary discussion may contribute to a better management.