CLINICOPATHOLOGIC CORRELATIONS Clinical Primary Pulmonary Hypertension Three Pathologic Types

SUMMARY Clinically, there is a group of patients with elevated pulmonary arterial pressure in whom the underlying cause is not ap-parent. The pulmonary arterial wedge pressure is not elevated. For such cases, the designation of primary pulmonary hypertension may be made clinically. From the clinical categorization of primary pulmonary hypertension, three distinct pathologic entities emerge, namely 1) plexogenic pulmonary arteriopathy, 2) recurrent pulmo-nary thromboembolism, and 3) pulmonary veno-occlusive disease. The plexogenic type is characterized initially by pulmonary arterial vasoconstriction with medial hypertrophy. Secondary THE EXISTENCE OF PULMONARY HYPER-TENSION is readily established by both clinical and in-vasive studies. In most instances, the underlying cause is ap-parent, the pulmonary hypertension being recognized as a feature of the underlying condition. There is a residuum o