Contribution of Raman Spectroscopy to diagnosis and grading of chondrogenic tumours

Background & Objectives: Raman Spectroscopy (RS) is a technique based on inelastic scattering of monochromatic light, usually a laser with wavelengths falling in the Ultraviolet-Visible-Near Infrared range. RS has demonstrated to be a label-free and non-destructive optical spectroscopy able to improve diagnostic accuracy in cancer diagnosis. We applied Raman spectroscopy imaging in order to discriminate and grade cartilaginous tumours. Methods: The study group included three patients affected by enchondroma (EC) and seven affected by chondrosarcoma (CS) (three grade 1, two grade 2 and two grade 3). We performed spectroscopy analyses with a Raman Imaging Microscope on formalin-fixed paraffin embedded unstained tumour tissue sections. Results: Several differences in the amino acid composition were highlighted between the tumour types. In particular, the amount of β–Carotene progressively reduced from EC to high-grade CS, while the degradation of collagen increased with the CS grade. Interestingly, Linear Discrimination Analysis algorithm revealed major differences in chemical composition between the group of EC-grade 1 CS and the group of grade 2-grade 3 CS. Conclusion: RS may be a useful tool in the histopathological analysis of cartilaginous tumours since it provides biochemical information related to tumourigenesis and progression of disease. Notably, the acquisition of a metastatic potential that characterises grade 2 and grade 3 CS was associated with a significantly different biochemical profile in comparison with Grade 1 CS and EC, that are considered benign or locally aggressive tumours. Our results may contribute to improve diagnostic accuracy and reduce inter-observer variability in the assessment of chondrogenic tumours.