Pulmonary complications of the IBD may include:
(1) tracheobronchitis (see previous section)
(2) abnormal pulmonary function tests
(3) bronchiectasis
(4) bronchiolitis obliterans with organizing pneumonia (BOOP)
(5) interstitial pneumonia with or without fibrosis
(6) eosinophilic pneumonia
(7) necrotic parenchymal nodules (necrobiotic nodules)
(8) serositis (pleuritis)
(9) thromboembolic disease
(10) vasculitis
(11) granulomatous lung disease
Pulmonary symptoms may worsen after colectomy (which may reflect heightened disease activity).
Differential diagnosis:
(1) drug-induced lung toxicity (methotrexate, 5-ASA, other). These can cause interstitial lung disease or eosinophilic pneumonia which may overlap with changes due to the IBD. These changes usually revert on discontinuation of the implicated drug.
(2) infectious pneumonia, which may be a complication of immunosuppression
(3) complications of smoking
(4) other lung disease
