Diagnosis of vulvar lesions by non-invasive optical analysis: a pilot study

Abstract

A procedure that could allow an early in vivo and non-invasive detection of vulvar lesions would be extremely useful. We tested an innovative optical method (Optiprobe), which uses a harmless, visible light source for the in vivo, on-line detection of minimal alterations in the structure of vulvar epithelium. A group of 3 female volunteers without gynecological symptoms were first screened to evaluate optical properties of normal vulvar tissue. Next, a group of 16 patients undergoing gynecological examination for vulvar lesions was evaluated by the Optiprobe at suspected sites before these sites were biopsied for histological analysis. Adjacent, non-involved sites were also measured to provide internal controls. Histological analysis of the biopsies identified one case that did not show obvious alterations, 4 cases of high-grade vulvar intraepithelial neoplasia (VIN), 5 cases of vulvitis, and 6 cases of lichen sclerosis (LS).The optical properties of the VIN cases were significantly different from those of controls, due to a decrease in the absorption spectra and an increase in the scattering spectra. In contrast, a significant increase in the absorption spectra and a decrease in the scattering spectra were observed in the cases of vulvitis. In the LS cases, the absorption spectra were as in controls, whereas the scattering spectra were significantly decreased. We conclude that the Optiprobe provides a useful tool for a rapid and non-invasive detection of vulvar alterations. The method should contribute to reduce the number of biopsies and to facilitate the long-term follow-up of vulvar lesions.

Keywords: absorption spectra; non invasive diagnosis; optical analysis; scattering spectra.; vulvar intraepithelial neoplasia.

Figure 1

Optical spectra of normal vulvar tissue vary between healthy women. Mean (bold line) and standard deviations (thin lines) of the absorption (A) and scattering coefficients (B) measured on 3–4 adjacent sites in each healthy volunteer (a, b and c are recordings from the 52-, 48- and 34-year old women, respectively.

Figure 2

(A–C) Absorption analysis discriminated VIN and inflammatory lesions, but not lichen sclerosis from normal tissue. (A) Mean (bold line) and standard deviations (thin lines) of absorption spectra obtained at sites featuring histology characteristics of VIN (A), inflammation (B) and lichen sclerosis (C). Absorption spectra of VIN and vulvitis (black) were significantly (p<0.001) different from those of controls spectra (gray), for light wavelengths of 400–700 nm. In contrast, absorption spectra of lichen sclerosis (black) were not different from those of controls (gray). (D–F) Mean (bold line) and standard deviations (thin lines) of percentage of change in absorption spectra between pathological and control sites were calculated for the 4 VIN (D), the 5 vulvitis (E), and the 6 lichen sclerosis sites (F). Graphs show that VIN lesions induced a significant decrease of absorption between 400 nm and 500 nm, whereas a significant increase was observed at inflammatory sites. No significant change was observed at lichen sclerosis sites.

Figure 3

(A–C) Scattering analysis discriminated VIN, inflammatory and lichen sclerosis lesions from normal tissue. Mean (bold line) and standard deviations (thin lines) of scattering spectra obtained in women diagnosed with VIN (A), inflammation (B) and lichen sclerosis (C). Scattering spectra of VIN sites, vulvitis sites and lichen sclerosis sites (black) were significantly (p<0.001) different from controls spectra (gray) for light wavelengths of 400–700 nm, 400–500 nm, and 500–700 nm, respectively. (D–F) Mean (bold line) and standard deviations (thin lines) of percentage change over control was calculated for the 4 VIN (D), the 5 vulvitis (E) and the 6 lichen sclerosis sites (F). Graphs show significant scattering variation in VIN, vulvitis and lichen sclerosis cases, for light wavelengths of 400–700 nm, 400–510 nm and 500–700, nm respectively.