In this article, we offer a novel classification of progressive changes in the connective tissue of dermis in vulvar lichen sclerosus (VLS) relying on quantitative assessment of the second harmonic generation (SHG) signal received from formalin fixed and deparaffinized tissue sections. We formulate criteria for distinguishing four degrees of VLS development: Initial‐Mild‐Moderate‐Severe. Five quantitative characteristics (length and thickness type I Collagen fibers, Mean SHG signal intensity, Skewness and Coherence SHG signal) are used to describe the sequential degradation of connective tissue (changes in the structure, orientation, shape and density of collagen fibers) up to the formation of specific homogeneous masses. Each of the degrees has a characteristic set of quantitatively expressed features. We focus on the identification and description of early, initial changes of the dermis as the least specific. The results obtained by us and the proposed classification of the degrees of the disease can be used to objectify the dynamics of tissue changes during treatment.

Multimodal optical coherent tomography grows popularity with researchers and clinicians over the past decade. One of the modalities is lymphangiography, which allows visualization of the lymphatic vessel networks within optical coherence tomography (OCT) imaging volume. In the present study, it is shown that lymphatic vessel visualization obtained from the depth-resolved attenuation coefficient distributions, corrected for the noise, shows improved contrast and detail in comparison with previously proposed approaches. We also argue that the two most popular approaches for lymphatic vessel visualization, namely simple intensity thresholding and vesselness calculation based on local Hessian matrix eigenvalues, imply different definitions of the lymphatic vessel's appearance in the OCT volume and lead to the different networks.

The aim of the study was to test the method of optical coherence tomography (OCT) for its ability to obtain images of blood and lymphatic vessels of the vulva.Materials and Methods. The study was performed using a multimodal optical coherence tomography device developed in the Institute of Applied Physics of the Russian Academy of Sciences (Nizhny Novgorod). In this setup, 3D images of 3.4×3.4×1.25 mm are created within 26 s. OCT angiography and OCT lymphangiography are based on the speckle structure analysis. Visualization of blood and lymphatic vessels does not require any additional contrast agents.A histological study of vulvar biopsy samples from two locations was performed in 3 patients without vulvar pathology and in 5 patients with vulvar lichen sclerosus; the results were then compared with 3D OCT images obtained at the same locations.Results. Using the multimodal OCT, we found that normal mucous membrane of the vulva had a well-developed network of blood and lymphatic vessels; their diameters were increasing with depth. In the subepithelial zone, only blood capillary loops could be seen, whereas lymphatic capillaries became detectable starting from a depth of 170 μm (submucosa layer).In the case of vulvar lichen sclerosus, the density of the blood vessel network decreases dramatically and the capillary loops in the subepithelial zone disappear. Lymphatic vessels become detectable at a depth of 300 μm, and only few thin vessels can be detected at depths of 300 to 600 μm. The results suggest that the presentation of blood and lymphatic vessels depends on the state of the vulvar connective tissue. Specifically, the number of blood and lymphatic vessels is reduced in areas of hyalinosis and sclerosis of collagen fibers.Conclusion. For the first time, using multimodal OCT, an in vivo study of blood and lymphatic vessels of the vulvar mucosa was performed on normal and lichen sclerosus-affected vulva; the obtained OCT images were then compared with histological images of the same tissues. The OCT method allows one to diagnose a zone of hyalinosis and sclerosis of collagen fibers characterized by an abnormally low number of blood and lymphatic vessels.

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