Carcinoma of the Lung
Pathology of COPD
Infections Involving the Airways
Review the different morphologic types of smoking-related lung cancers.
Review major highlights of the new (and not universally adopted) classification of lung adenocarcinomas.
Review the pathologic features of COPD.
Review the pathologic features of asthma.
Review the pathologic features of bronchopneumonia.
Review the pathologic features of infectious bronchiolitis and constrictive bronchiolitis.
Review the pathologic features of aspiration.
The common smoking-induced lung cancers include squamous cell carcinoma, adenocarcinoma, small cell carcinoma, and large cell undifferentiated carcinoma. Bronchoalveolar cell carcinoma is a variant of adenocarcinoma in which there is growth of carcinoma cells along alveolar walls. A new classification of pulmonary adenocarcinomas proposes to replace the term bronchoalveolar carcinoma with adenocarcinoma in situ because these tumors are noninvasive and are 100% curable with local excision. Carcinoids are nonsmoking-related neuroendocrine tumors that are usually low grade malignancies, most commonly found in the large airways. COPD includes the pathologic entities of emphysema, small airway remodeling, bronchial mucus gland hypersecretion (clinical chronic bronchitis), and vascular remodeling associated with pulmonary hypertension, of which emphysema and small airway remodeling are associated with airflow obstruction. In asthma a variable combination of increased airway smooth muscle, thick basement membrane, mucus metaplasia with mucus hypersecretion, epithelial denudation, and eosinophil infiltration are found. Infectious bronchiolitis is characterized most commonly by an acute luminal neutrophil exudate with a chronic inflammatory cell infiltrate in the airway wall. Bronchopneumonia shows neutrophils in the lumens of respiratory bronchioles and surrounding parenchyma. In aspiration, food particles and bronchiolitis obliterans organizing pneumonia are often present in addition to neutrophils, but pure acid aspiration can lead to diffuse alveolar damage (clinical ARDS). Constrictive bronchiolitis demonstrates narrowing or complete obliteration of the lumens of respiratory bronchioles by fibrous tissue with resulting fixed airflow obstruction.