) Pulmonary vascular sclerosis refers to the vascular changes associated with pulmonary hypeension. Elevation of the mean pulmonary aerial pressure is the result of endothelial dysfunction and vascular changes. The vascular changes vary with the size of the vessel. The main aeries have atheromas that are similar to systemic atherosclerosis, but are not as severe. Medium-sized aeries show intimal thickening and neomuscularization. Smaller aeries and aerioles show intimal thickening, medial hyperophy, and reduplication of the internal and external elastic membranes. A distinctive aeriolar change, a plexiform lesion, consists of intraluminal angiomatous tufts that form webs. This pattern is thought to be diagnostic of primary hypeension The changes of pulmonary vascular sclerosis may be primary or secondary. Primary pulmonary vascular sclerosis almost always occurs in young women, who develop fatigue, syncope (with exercise), dyspnea on exeion (DOE), and chest pain. Secondary sclerosis may occur at any age, and symptoms depend on the underlying cause. Possible causes include ceain types of hea disease, such as mitral valve disease, left ventricular failure, and congenital valvular disease with left-to-right shunt, as well as ceain types of pulmonary disease, such as chronic obstructive or interstitial lung disease and recurrent pulmonary emboli. Pulmonary hypeension is also associated with diet pills (Redux and Fen-Phen), while "exotic" causes include Crotalaria spectabilis ("bush tea") and adulterated olive oil Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition.