pulmonary disorders
Bronchiectasis
Etiology of Bronchiectasis
Bronchiectasis is best considered the common end-point of various disorders that cause chronic airway inflammation. Bronchiectasis may be Diffuse: Affecting many areas of the lungs Focal: Appearing in only 1 or 2 lung areas Diffuse bronchiectasis develops most often in patients with genetic, immunologic, or anatomic defects that affect the airways. The cause of many cases appears initially to be idiopathic, probably partly because onset is so slow that the triggering problem is not readily evident at the time bronchiectasis is recognized. However, after through investigation using newer genetic and immunologic testing,, an etiology is more often found in these idiopathic cases. Cystic Fibrosis (CF) is commonly associated with diffuse bronchiectasis, and previously undiagnosed CF may account for up to 20% of idiopathic cases. Even patients who are heterozygous, who typically have no clinical manifestations of CF, may have an increased risk of bronchiectasis. Immunodeficiencies such as Common Variable Immunodeficiency (CVID) (CVID) may also lead to diffuse disease. Rare abnormalities in airway structure may lead to diffuse bronchiectasis. Congenital defects in mucociliary clearance such as primary ciliary dyskinesia (PCD) syndromes may also be a cause, explaining almost 3% of previously idiopathic cases. Diffuse bronchiectasis sometimes complicates common autoimmune disorders, such as Rheumatoid Arthritis (RA) or Allergic Bronchopulmonary Aspergillosis (ABPA) , a hypersensitivity reaction to In countries where tuberculosis is common, most cases are probably caused by Tuberculosis (TB) , particularly in patients with impaired immune function due to Focal bronchiectasistypically develops as a result of untreated pneumonia or obstruction (eg, due to foreign bodies, tumors, postsurgical changes, lymphadenopathy). Mycobacteria (tuberculous or nontuberculous) can both cause focal bronchiectasis and colonize the lungs of patients with bronchiectasis due to other disorders (see table). 