Immunohistochemical expression of endothelial nitric oxide synthase and C-kit in the placenta of complete hydatidiform mole.

Complete hydatidiform mole is an abnormal conceptus characterized by hydropic villi accompanied by proliferating trophoblasts. Its pathogenesis is largely unknown. Endothelial nitric oxide synthase is induced by vascular endothelial growth factor and has been implicated in the pathogenesis of preeclampsia and other physiologic conditions in the placenta. C-kit is the tyrosine kinase receptor and is involved in tumor formation elsewhere in the body. Using standard immunohistochemical protocols, we studied the expression of C-kit and endothelial nitric oxide synthase in the placenta of 10 patients with complete hydatidiform mole. Cytoplasmic and nuclear staining with endothelial nitric oxide synthase was identified in the cytotrophoblast and intermediate trophoblast layers in all cases, with high staining in 7/10 and 6/8 cases, respectively. Minimal staining is identified in the syncytiotrophoblast layer. Hofbauer stromal cells were identified in 9 cases and showed low staining intensity in 7/9 cases. Cytoplasmic C-kit staining was diffuse and of low intensity. The cytotrophoblast, the syncytiotrophoblast, intermediate trophoblast, and the stromal cells had low C-kit staining intensity in 8/10, 8/10, 7/9, and 5/9 cases. These results indicate that C-kit and endothelial nitric oxide are expressed in the placentas of complete hydatidiform mole and may play a role in the pathogenesis of trophoblastic proliferation in this condition.