In vivo Fluorescence Spectroscopy of Nonmelanoma Skin Cancer¶

Abstract

In vivo and ex vivo tissue autofluorescence (endogenous fluorescence) have been employed to investigate the presence of markers that could be used to detect tissue abnormalities and/or malignancies. We present a study of the autofluorescence of normal skin and tumor in vivo, conducted on 18 patients diagnosed with nonmelanoma skin cancers (NMSC). We observed that both in basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) the endogenous fluorescence due to tryptophan residues was more intense in tumor than in normal tissue, probably due to epidermal thickening and/or hyperproliferation. Conversely, the fluorescence intensity associated with dermal collagen crosslinks was generally lower in tumors than in the surrounding normal tissue, probably because of degradation or erosion of the connective tissue due to enzymes released by the tumor. The decrease of collagen fluorescence in the connective tissue adjacent to the tumor loci was validated by fluorescence imaging on fresh-frozen tissue sections obtained from 33 NMSC excised specimens. Our results suggest that endogenous fluorescence of NMSC, excited in the UV region of the spectrum, has characteristic features that are different from normal tissue and may be exploited for noninvasive diagnostics and for the detection of tumor margins.

In vivo measurements of diffuse reflectance and time‐resolved autofluorescence emission spectra of basal cell carcinomas

“…This observed difference is in agreement with the work of Rajaram et al [33] who saw decreased diffuse reflectance and autofluorescence (with 337 nm excitation) from BCCs compared to the corresponding normal skin. Similarly Brancaleon et al reported reduced autofluorescence intensity in BCCs and SCCs, both in vivo (excitation at 350 nm) and in freshly resected frozen samples (360 nm excitation), which they attributed to a (histologically visible) loss of collagen and elastin [56].…”

“…Much work has been done in this field including single- [56] and multi-photon imaging [57][58][59][60], fluorescence lifetime imaging [24] and also combinations of several non-linear imaging modalities [61][62][63][64]. Clearly imaging holds advantages over point spectroscopy in terms of the spatial resolution, the morphological information provided and the potential to rapidly identify margins.…”

Laser‐induced fluorescence spectroscopy for in vivo diagnosis of non‐melanoma skin cancers

“…They indicated that the fluorescence intensity from BCC was significantly lower than that of normal surrounding tissues. Brancaleon et al [15] used 295 and 350 nm UV light to examine in vivo fluorescence intensity (corrected by reflectance spectra) of normal and cancer in 18 patients with squamous cell and BCC. Using 350 nm, the emission intensity from tumor was much weaker than that of surrounding normal tissue.…”

“…Recently, non-laser based fluorescence spectroscopy at the UV excitation wavelength of 370 nm was applied to show that basal cell carcinoma (BCC) had significantly lower fluorescence intensity than normal skin [14]. In another non-laser based fluorescence study, UV excitations of 295 and 350 nm was used to differentiate BCCs and SCCs from normal skin [15]. Using the reflectance spectra to correct the fluorescence emission for pigmentation of skin, they showed significant differences between normal and cancerous spectra.…”

Biophotonics for dermatology: science & applications

“…Even though it has been clear that the successful development of photomedicine relies on indepth investigations of photobiological responses, only recent technological developments enabled thorough investigations of tissue optics [1][2][3]. As skin is the largest and most accessible human organ, it has been explored using confocal [4] and nonlinear [5] microscopy; reflectance [6], fluorescence [7], and Raman [8] spectroscopy; optical coherence tomography [9]; polarization imaging [10][11][12]. Fundamental theoretical and experimental discoveries and observations [13][14][15] have contributed to the advent and development of dermatological and cosmetic therapies [16].…”