Spectroscopic and Imaging Characteristics of Pigmented Non-Melanoma Skin Cancer and Melanoma in Patients with Skin Phototypes III and IV

Abstract

Introduction: Non-melanoma skin cancer is the most common malignancy worldwide. Differentiating between malignant and benign skin tumors, however, can be challenging. As a result, various auxiliary tools have been developed to aid in the diagnosis of cutaneous neoplasms. Here, skin tumors were investigated through analysis of their digital image histograms and spectroscopic response under ultraviolet (UV) and white light-emitting diodes (LEDs).

Methods: Fifty tumoral lesions were spectroscopically and histologically studied. For optical studies, UV at 375 nm and white LEDs were used to illuminate the lesions. Commercial cameras were used for imaging, and a miniature spectrometer with a bifurcated optical fiber was used for spectroscopic measurements.

Results: In this study, the intensity histograms of the images taken under white and UV illumination and the spectroscopic response under white light showed clear differences between pigmented basal cell carcinoma (BCC), intradermal melanocytic nevus (IDN), and melanoma lesions for skin phototypes III and IV. However, there was little difference in their spectroscopic response to the UV LED.

Conclusion: We found differences in the intensity and shape of diffuse reflectance spectra of pigmented BCC, IDN, and melanoma lesions in patients with skin phototypes III and IV. Also, images taken under UV and white light were helpful for differentiation of these pigmented lesions. Additional research is needed to ascertain the clinical utility of these tools for skin cancer diagnosis.

Keywords: Digital images; Melanoma; Skin cancer; Spectroscopy.

Fig. 1

Processing of the digital image of a toe lesion, taken under white light. Images of the lesion and the perilesional zone, together with their respective RGB histograms, are also shown

Fig. 2

Processing of digital image of a toe skin lesion under UV light. Images of the lesion and the perilesional zone are also shown, with their respective histograms

Fig. 3

Cheek (A) and forehead (B) diffuse reflectance spectra for patients with skin phototypes III and IV

Fig. 4

Diffuse reflectance spectra of cutaneous pigmented IDN, BCC, and melanoma lesions in patients with skin phototypes III (A) and IV (B)

Fig. 5

Measured spectral emission of the NCU033AT ultraviolet LED (Nichia Corp.). The inset is a zoom of the right tail of the UV main peak

Fig. 6

Measured spectra under UV illumination for pigmented skin lesions in patients with skin phototypes III (A) and IV (B)

Fig. 7

Digital images of a non-pigmented BCC taken under white LED light (A) and UV light (B). C Spectra measured on the lesion and on the perilesional skin using the UV light source

Fig. 8

Images of some of the examined skin lesions. Melanoma under white light (A) and under UV illumination (B). BCC under white (C) and UV (D) light

Fig. 9

Total intensity ratios of digital images taken in patients with skin phototype III under white light (A) and UV light (B). P-BCC pigmented basal cell carcinoma, NP-BCC non-pigmented basal cell carcinoma, SCC squamous cell carcinoma, IS-SCC in situ squamous cell carcinoma, IDN intradermal nevus. a p < 0.05, compared to P-BCC; b p < 0.05, compared to NP-BCC; c p < 0.05, compared to SCC; d p < 0.05, compared to IS-SCC; e p < 0.05, compared to IDN

Fig. 10

Total intensity ratios of digital images in patients with skin phototype IV, recorded under white (A) and UV (B) light. BCC basal cell carcinoma, SCC squamous cell carcinoma, MM malignant melanoma, IDN intradermal nevus. a p < 0.05, compared to BCC; b p < 0.05, compared to SCC; c p < 0.05, compared to MM; d p < 0.05, compared to IDN