Pulmonary complications of inflammatory bowel disease

INTRODUCTION

A variety of conditions arise outside of the gastrointestinal tract that are associated with inflammatory bowel disease (IBD); these are termed extraintestinal manifestations of IBD (table 1). Involvement of the respiratory tract, although relatively rare, is increasingly recognized in patients with inflammatory bowel disease (IBD) since the original report in 1976 of six patients with unexplained chronic purulent sputum production [1]. These abnormalities are generally related to the underlying bowel disease, although interstitial lung disease can also be induced by administration of certain drugs, including sulfasalazine, 5-aminosalicylic acid, methotrexate, azathioprine, and infliximab [2-6].

The pulmonary complications of IBD and those related to the various therapies for IBD are discussed here. An approach to interstitial pneumonitis and a discussion of the clinical manifestations of Crohn's disease and ulcerative colitis are provided separately. (See "Clinical manifestations, diagnosis and prognosis of Crohn's disease in adults" and "Clinical manifestations, diagnosis, and prognosis of ulcerative colitis in adults".)

PRIMARY RESPIRATORY INVOLVEMENT

Pulmonary complications of IBD include airway inflammation involving small and large airways, pulmonary parenchymal disease, and serositis [7,8]. In one study, reporting 33 new cases and reviewing an additional 98 cases from the literature, approximately 41 percent of the patients presented with some form of airway inflammation, 27 percent with lung parenchymal involvement, and 17 percent had involvement of the pleura; an additional 15 percent had myo/pericarditis (table 2) [9].

The pathogenesis of the pulmonary parenchymal disease and the serositis is unknown. However, the more common airway inflammatory changes have been thought to represent the same type of inflammatory changes that occur in the bowel [10]. (See "Immune and microbial mechanisms in the pathogenesis of inflammatory bowel disease" and "Immunologic basis for extraintestinal manifestations in inflammatory bowel disease".)

Airway inflammation — Inflammation of the trachea, bronchi, and bronchioles can occur in inflammatory bowel disease, with bronchial involvement being most common [9-12].