As a premalignant lesion with distinct histological grades preceding the development of cancer, this entity affords an opportu nity to dissect the natural history of the development of the angiogenic phenotype in a naturally occurring neoplasia. MATERIALS AND METhODS

(CIN II), and severe dysplasia or carcinoma in situ (CIN III), depend ing upon the extent of nuclear abnormality and the degree to which the differentiated upper layers of the epithelium are replaced by abnormal cells (8). The lesions differ from cancer in that the abnormal cells are confined to the epithelium and do not transgress the basement mem brane beneath it. Both cervical dysplasia and cancer are strongly correlated with the presence of HPV, particularly of the subtypes 16 and 18 (9). Clinically, dysplastic lesions are detected by Papanicolaou smear screening and localized by stereoscopic examination of the cervix in a technique known as colposcopy. As viewed by colposcopy, lesions appear as white plaques after the application of acetic acid and can be graded by the presence of red patterns of punctation or mosa icisrn on the white background, which represent vascular structures within the dysplasia (10). On occasion, atypical vessels can be seen colposcopically on the surface of the lesion and are associated with frank invasion on biopsy (11). The presence of macroscopic vascular patterns with dysplastic lesions would suggest that an angiogenic event is associated with dysplasia. This study was designed to test this assumption. As a premalignant lesion with distinct histological grades preceding the development of cancer, this entity affords an opportu nity to dissect the natural history of the development of the angiogenic phenotype in a naturally occurring neoplasia.