Differential diagnosis of nonmelanoma pigmented skin lesions based on harmonic generation microscopy

Abstract

Abstract. In vivo harmonic generation microscopy (HGM) has been applied successfully in healthy human skin and can achieve a submicron resolution, similar to histopathologic examination, even at a penetration depth up to 270 μm. This study aims to investigate the clinical applicability of HGM imaging for differential diagnosis of nonmelanoma pigmented skin lesions. A total of 42 pigmented skin tumors, including pigmented basal cell carcinoma, melanocytic nevus, and seborrheic keratosis were evaluated by HGM ex vivo or in vivo. Based on the standard histopathologic characteristics, we established the corresponding HGM imaging criteria for each pigmented tumor. Diagnostic performance of HGM for differentiating nonmelanoma pigmented skin tumors was evaluated through the observers' direct general assessment (overall evaluation) or the presence of two imaging criteria with the highest sensitivity and specificity (major criteria evaluation). Our results show that, based on the direct general assessment, the sensitivity is 92% [95% confidence interval (CI): 67 to 97%] and the specificity is 96% (95% CI: 83 to 99%); by major criteria evaluation, 94% sensitivity (95% CI: 70 to 99%) and 100% specificity (95% CI: 87 to 100%) are achieved. Our study indicates that HGM serves as a promising histopathological examination tool for noninvasive differential diagnostics of nonmelanoma pigmented skin tumors. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Advances and challenges in label-free nonlinear optical imaging using two-photon excitation fluorescence and second harmonic generation for cancer research

“…Meanwhile THG, like SHG, occurs when three photons are fused to create a single photon at three times the frequency or one third the wavelength. THG had been employed by Tsai et al [147] and they were able to differentiate between pigmented basal cell carcinoma, seborrhoeic keratosis and melanocytic nevi. It is highly probable that 3PEF and THG will have a significant role to play in the future of NLOI based cancer research, as the required technology is currently available.…”

“…But the avenue of three photon based MPEF (or 3PEF) [145,146] and third Harmonic Generation [147][148][149][150] (THG) is yet to be fully explored. The biggest advantage here is that 3PEF based label-free NLOI use longer NIR wavelengths than those employed by TPEF based NLOI.…”

In vivo third-harmonic generation microscopy study on vitiligo patients

“…A least-invasive imaging tool, which can perform high-resolution virtual biopsy examination, is thus highly desired. Recently, optical imaging techniques, such as reflection confocal microscopy, 11 optical coherent tomography, 12 two-photon fluorescence microscopy, 13 and THGM, 14 have been widely applied for high-resolution in vivo skin imaging. With the excitation wavelength located at the 1300-nm high penetration window and a cubic nonlinearity for superior signal-to-background ratio imaging at deep tissues, THGM provides slide-free and label-free clinical imaging in human skin with a high 3-D resolution.…”

Third harmonic generation microscopy of cells and tissue organization

“…THG-based diagnosis of basal cell carcinoma in vivo depends upon the polymorphous variations in the size and shape of transformed cells, compared to normal tissue and the presence of peripheral palisading cells (Tsai et al, 2014). An increase in the size of cells and nuclei in intact skin are characteristics of aging tissue, which can be quantified in vivo based on THG analyses (Liao et al, 2013).…”