Idiopathic pulmonary fibrosis (IPF)

Interstitial lung disease (ILD), also called diffuse parenchymal lung disease, is a diverse group of nonmalignant disorders causing inflammation and scarring of the alveolar interstitium, presenting as subacute to chronic exertional dyspnea and nonproductive cough. Diagnosis rests on pulmonary function testing plus high-resolution CT pattern recognition; management is exposure removal, glucocorticoids for inflammatory disease, antifibrotic therapy for progressive fibrotic disease, oxygen for hypoxemia, and early transplant referral.

Hypersensitivity pneumonitis is a mixed type III/IV immune reaction to repeated inhalation of an organic antigen in a sensitized host, producing noncaseating granulomas and bronchiolocentric inflammation. Removal of the offending antigen is the essential first step in treatment; glucocorticoids are added for significant hypoxemia or symptom burden, and unremitting exposure can progress to fibrotic lung disease indistinguishable from idiopathic pulmonary fibrosis.

Sarcoidosis is a multisystem granulomatous disease of unknown cause defined by noncaseating granulomas, most commonly involving the lungs and hilar lymph nodes. Most patients are asymptomatic or have a self-limited course staged by chest radiograph; symptomatic organ-threatening disease is treated with systemic glucocorticoids, with methotrexate or another steroid-sparing agent added for glucocorticoid-refractory or glucocorticoid-intolerant disease.

Asbestos-related lung disease covers a spectrum from calcified pleural plaques and benign pleural effusion to progressive asbestosis (a fibrotic interstitial lung disease) and the malignancies bronchogenic carcinoma and mesothelioma, all following inhalational asbestos exposure with latencies of 10 to 40 years. Diagnosis rests on an occupational exposure history plus imaging showing a lower-lobe usual-interstitial-pneumonia pattern or calcified pleural plaques; management of asbestosis is supportive with smoking cessation and oxygen, while mesothelioma requires pleural biopsy and multidisciplinary oncologic staging.

Rheumatoid arthritis is a chronic systemic autoimmune disease causing symmetric small-joint polyarthritis of the hands and feet that spares the distal interphalangeal joints, with morning stiffness over an hour. Diagnosis combines the ACR/EULAR classification criteria with rheumatoid factor, anti-CCP antibody, and radiographs. Treat-to-target management anchors on methotrexate, escalating to a biologic or targeted synthetic disease-modifying antirheumatic drug when remission is not reached.

Cor pulmonale is right ventricular structural and functional impairment caused by group 3 pulmonary hypertension from chronic lung disease or hypoxemia. Diagnosis rests on echocardiographic screening confirmed by right heart catheterization, and management centers on treating the underlying lung disease, correcting hypoxemia, and cautious diuresis.

Pulmonary hypertension is a resting mean pulmonary artery pressure of 20 mmHg or greater on right heart catheterization, classified into five WHO groups by mechanism. Diagnosis requires screening echocardiography followed by confirmatory right heart catheterization, and management is group-specific, with PAH-targeted vasodilator therapy reserved for group 1 disease.

Chronic obstructive pulmonary disease is a persistent, usually progressive airflow obstruction driven mainly by cigarette smoke, confirmed by a postbronchodilator FEV1/forced vital capacity (FVC) ratio below 0.70 and staged by GOLD spirometric grade plus symptom/exacerbation group. Maintenance management is a stepwise ladder of smoking cessation, long-acting bronchodilators, add-on inhaled glucocorticoid, roflumilast, or azithromycin for frequent exacerbators, long-term oxygen for resting hypoxemia, and vaccination, with acute exacerbations managed as a separate protocol.

Lung cancer is the leading cause of cancer death worldwide, split into non-small cell lung cancer (NSCLC, 80% of cases: adenocarcinoma, squamous cell, large cell) and small cell lung cancer (SCLC, 10-15%), both driven overwhelmingly by cigarette smoking. Diagnosis requires tissue histopathology, staging drives treatment (TNM staging for NSCLC, limited versus extensive stage for SCLC), and management ranges from lobectomy in early-stage disease through concurrent chemoradiation and consolidation immunotherapy in locally advanced disease to targeted tyrosine kinase inhibitors, immune checkpoint inhibitors, or platinum-based chemotherapy in metastatic disease.

Heart failure is a clinical syndrome of impaired cardiac filling or ejection causing congestion and reduced perfusion, classified by ejection fraction. Diagnosis integrates symptoms, signs, natriuretic peptides, and echocardiography, and treatment of reduced-ejection-fraction disease is quadruple guideline-directed therapy, with device therapy and cause-specific management.