Definition
• Mean pulmonary arterial pressure >25 mm Hg at rest
Clinical features
Epidemiology
• Pulmonary hypertension may be due to a wide range of causes and is grouped clinically in five categories (see Appendix Table 3)
Presentation
• Dyspnea on exertion
• Edema, angina, and syncope are possible with more severe disease
Pathology
Gross
• Large pulmonary arteries may demonstrate atherosclerosis
Histology
• Medial hypertrophy and concentric or eccentric intimal fibrosis of the pulmonary arteries are seen in all forms of pulmonary hypertension
• Other lung changes consistent with the primary disease may be seen
Immunopathology/special stains
• Elastic and trichrome stains highlight the medial and intimal changes
Fig 1 Pulmonary hypertension. Atherosclerotic plaques in large pulmonary arteries in an explanted lung.
Fig 2 Pulmonary hypertension. Intimal fibrosis and medial hypertrophy are illustrated here on H&E (A), trichrome (B), and elastic (C) stains. Note that the elastic stain is most helpful.