Pivotal clinical dilemmas in collagen vascular diseases associated with interstitial lung involvement

The connective tissue disorders (CTDs), also called collagen vascular diseases (CVDs), represent a heterogeneous group of immunologically mediated inflammatory disorders with a large variety of affected organs. Individuals with a CTD (rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, Sjögren's syndrome, polymyositis/dermatomyositis and mixed connective tissue disease) are susceptible to respiratory involvement. When the lungs are affected, an increasing mortality and morbidity in CVDs occurs. Interstitial lung disease (ILD) is established as a clinical corollary across the spectrum of CTDs, with an overall incidence estimated at 15%. Therefore, pivotal clinical dilemmas remain in the evaluation and management of ILD involvement in CVDs. Critical questions are the presence of fibrosis and whether the disease is clinically significant. Moreover, the clinician has to decide if treatment is warranted and which is the best therapeutic approach. The use of additional tests, such as pulmonary function tests, high-resolution computed tomography scan, bronchoalveolar lavage fluid and surgical lung biopsy, deserves better discussion. The present review focuses on establishing the diagnosis of ILD in CTD, and on evaluating disease activity and prognosis. This will provide the basis for therapeutic decisions that will be discussed, including an overview of recent advances.