Recent advances in nonlinear optical techniques for metastatic melanoma diagnosis and mechanistic studies

Melanoma, a highly aggressive form of skin cancer, is characterized by complex metabolic reprogramming that drives its metastatic potential and therapy resistance. While localized melanoma can be treated effectively, metastatic melanoma remains largely incurable, creating an urgent need for methods enabling early diagnosis and prognosis. In this review, we summarize recent efforts toward addressing these clinical challenges by nonlinear optical techniques, particularly pump-probe microscopy and vibrational spectroscopy, developed for in vivo investigation of key molecular changes in melanoma progression. These techniques enable label-free, real-time imaging of two critical components in melanoma progression: melanin and lipid droplets, respectively, providing unique insights into molecular mechanisms of melanoma progression. Future research directions focus on transforming these imaging techniques to enhance their clinical applicability and further investigation of the metabolic vulnerabilities of melanoma.