Low-grade lesions are characterized by a smooth surface with indistinct borders or irregular, “feathered” or “geographic” outer borders. Internal borders within the lesion are not present. Satellite aceto-white lesions arising within the mature squamous epithelium outside of the transformation zone are almost always low-grade.

Lugol’s iodine application is negative in immature squamous metaplasia, atrophy, and cervical intraepithelial neoplasia due to a lack of glycogenation of the squamous epithelium. A speckled or tortoise shell appearance, indicating partial iodine uptake, is associated with slight aceto-white change may be immature metaplasia or low-grade intraepithelial neoplasia. Complete iodine negativity is more suggestive of high-grade neoplasia.

Low-grade lesions are either featureless or have fine mosaicism or punctation. The vascular change has a regular pattern with equal intercapillary distances. If the intercapillary distance is markedly increased and irregular it is more likely a high-grade lesion. As a general rule, atypical vessels such as nonarborizing comma or hairpin vessels are not present in low-grade lesions. A notable exception is the prominent vascularity that may be present with inflammatory reparative lesions and the central capillary loops of condyloma.

It is a general rule that the most severe area of the lesion is the most proximal to the squamo-columnar junction. The difficulty lies in learning to distinguish low-grade lesions from immature metaplasia which also exhibits aceto-whitening and fine vascular patterns. With experience, recognition of benign variants like immature metaplasia, cervicitis, atrophy, and pregnancy changes that mimic neoplasia can be accomplished. In fact, the distinction is often based on the degree of subtle colposcopic findings and biopsy is often necessary to confirm the diagnosis. Due to the variability of the colposcopic appearance of low-grade lesions, the accuracy and reproducibility of diagnosis is less than that of higher grade lesions. Several systems exist to help distinguish clinically significant lesions from benign nonneoplastic variants and to grade the severity of lesions. An easy to learn, reproducible system is Reid’s colposcopic index, which assesses margin, color, vascular patterns and iodine uptake.

Walker P, Dexeus S, DePalo G, et al. International terminology of colposcopy: An updated report from the international federation for cervical pathology and colposcopy. Obstet Gynecol 2003;101(1): 175-7.

Apgar BS, Spitzer M, Brotzman GL (eds):. Colposcopy Principles and Practice. An Integrated Textbook and Atlas. Philadelphia, PA, W.B. Saunders Company, 2002.

Burghardt E, Pickel H, Girardi F: Colposcopy-Cervical Pathology: Textbook and Atlas. 3rd ed. New York, Thieme, 1998.

Reid R, Scaizi P: Genital warts and cervical cancer. VI. An improved colposcopic index for differentiating benign papillomaviral infections from high-grade cervical intraepithelial neoplasia. Am J Obstet Gynecol 1985;153:611.