Dermatofluoroscopy diagnostics in different pigmented skin lesions: Strengths and weaknesses.

BACKGROUND: The melanin fluorescence of skin lesions is measurable with two-photon excitation, a process termed dermatofluoroscopy, which has shown a shift from the green spectra in benign melanocytic lesions to the red spectra in melanoma. This study addressed the question as to which kind of pigmented lesions can be correctly diagnosed as melanin-bearing malignant tumors. METHODS: 476 pigmented lesions including 101 cutaneous melanomas were analyzed with dermatofluoroscopy, measuring the melanin fluorescence in a grid-like fashion with a separation of measurement points of 0.2 mm. The results of the dermatofluoroscopy are presented as a diagnostic score with a cut-off score of ≥ 28 for the diagnosis of melanin-bearing malignant tumors, and were compared to the gold standard of histopathology. RESULTS: A highly significant difference (p < 0.0001) between the diagnostic scores of different skin tumors was found. Dermatofluoroscopy scores showed the highest sensitivity for melanomas (92.1 %). Interestingly, most pigmented basal cell carcinomas (BCCs, 88.9 %) were diagnosed as melanin-bearing malignant tumors. A higher sensitivity for the correct diagnosis was observed in older patients (≥ 53 years, p = 0.003), in patients with skin tanning (p = 0.025), and in patients with freckles during childhood (p = 0.046). CONCLUSIONS: Two-photon fluorescence is an innovative technique for the diagnosis of pigmented skin lesions, and shows a high sensitivity for detection of melanomas and pigmented BCCs.

Study protocol for a prospective, non-controlled, multicentre clinical study to evaluate the diagnostic accuracy of a stepwise two-photon excited melanin fluorescence in pigmented lesions suspicious for melanoma (FLIMMA study).

INTRODUCTION: Non-invasive, nanosecond, stepwise two-photon laser excitation of skin tissue was shown to induce melanin fluorescence spectra that allow for the differentiation of melanocytic nevi from cutaneous melanoma. METHODS AND ANALYSIS: This prospective, non-controlled, multicentre clinical study is performed to evaluate the diagnostic performance of the stepwise two-photon excited melanin fluorescence in the detection of cutaneous melanoma. The comparator will be the histopathological diagnosis. A total of 620 pigmented skin lesions suspicious for melanoma and intended for excision will be enrolled. ETHICS AND DISSEMINATION: Ethics approval was provided by the local ethics committees of the medical faculties of the University of Tuebingen, Heidelberg and Berlin. STUDY REGISTRATION: The FLIMMA study NCT02425475.