Monoclonal endothelial cell proliferation is present in primary but not secondary pulmonary hypertension.
Lee SD, Shroyer KR, Markham NE, Cool CD, Voelkel NF, Tuder RM. Monoclonal endothelial cell proliferation is present in primary but not secondary pulmonary hypertension. J Clin Invest. 1998 Mar 01; 101(5):927-34.