Light and electron microscopy of varicose vessels and telangiomas in the nasal mucosa of habitual nosebleeders.

Biopsy specimens of abnormal vessels in the nasal mucosa of 42 habitual nosebleeders (22 with telangiomas, 20 with varicose vessels) were examined with light and electron microscopy. There were no specific morphologic features that distinguished the wall structure of solitary varicose vessels from that of telangiomatous lesions consisting of multiple vessel branches. Thus, in both categories of vascular malformations a disproportionately thin and simple wall lined the large lumina. Mostly, the endothelium was the only component in the wall. The endothelium could consist of extremely thin, seemingly degenerating, cells that at some points even failed to form a continuous tunic. At other areas of the same vessel circumference patches of thick, organelle-rich, 'active' endothelial cells could be seen and endothelial cells with intermediate structural characteristics were also found. It is suggested that these endothelial cell appearances represent different stages of cellular proliferation, maturation, and ageing, i.e. turnover. The periendothelial lamina was occasionally multilayered. The large, thin-walled abnormal vessels were covered with scarce connective tissue and a rather thin epithelium. For simple mechanical reasons it is obvious that bleeding, i.e. vessel wall rupture, is easily elicited in these vascular channels and that control of hemorrhage is defect due to the absence of a true muscular media. The findings give rise to interesting questions as to the initiation and control of the abnormal angiogenic response(s) in the nasal mucosa manifested clinically as recurrent epistaxis.