Introduction to connective tissue diseases

Pleuropulmonary involvement by connective tissue diseases (CTD) is varied and includes pleural, interstitial, bronchial/bronchiolar and vascular manifestations. Common patterns of involvement overlap with those of idiopathic lung disease. They include patterns of nonspecific interstitial pneumonia (NSIP), lymphocytic interstitial pneumonitis (LIP), organizing pneumonia (OP), usual interstitial pneumonia (UIP), diffuse alveolar damage (DAD), chronic bronchiolitis, pulmonary capillaritis with alveolar hemorrhage and primary pulmonary hypertension among others (see Table 1). Some patterns (e.g. OP and NSIP) can occur in all CTD although their incidences, as pulmonary manifestations, differ greatly between individual disorders. This chapter reviews common and rare pulmonary manifestations of CTDs. Radiological and histological features of individual patterns of interstitial lung disease (e.g. NSIP pattern) are similar to those of their idiopathic counterparts (see Chapter 10). Accordingly this chapter will refer to such patterns but will not repeat detailed descriptions of the pathology. The status of Behçet syndrome, inflammatory bowel disease, as well as some dermatological conditions (e.g. Sweet syndrome, pyoderma gangrenosum) as components of CTD is less clear. They may have pulmonary and other systemic manifestations and are also briefly discussed.