This is a cross section pathology specimen from a patient with right ventricular hypertrophy due to idiopathic pulmonary hypertension. Note the thickened right ventricular free wall and papillary muscle along with the dilation of the right ventricular cavity. Note also the much straightened ventricular septum.
Histologic section of a pulmonary artery - lung biopsy
This histologic section of a pulmonary artery from a lung biopsy shows medial and intimal fibrosis. It may vary in degree and extent from one medium size pulmonary artery to another. Concentric laminar intimal fibrosis, as shown here, can be seen in pulmonary hypertension from many causes.
Plexiform lesion
This histologic section of a pulmonary artery shows the typical pathology found in idiopathic pulmonary hypertension, called plexogenic pulmonary arteriopathy. The pathogenesis is as yet unknown, but uncontrolled proliferation of the vascular smooth muscle and endothelium occur. This plexiform lesion may also be seen in pulmonary hypertension associated with congenital heart disease. The arterial wall is thin and the cavity occupied by proliferating cells packed around slit-like luminal spaces. The proliferating cells are often glued together with fibrinoid material. Beyond the plexus, the artery continues as a widely dilated tortuous and extremely thin wall channel. The lesion probably develops on the basis of fibrinoid necrosis. Plexiform lesions are considered irreversible and, when found, indicate a grave prognosis.