Identification of Diagnostic Metabolic Signatures in Thyroid Tumors using Mass Spectrometry Imaging

“Gray zone” category tumors in thyroid follicular tumors are difficult to diagnose, especially to distinguish between follicular thyroid adenoma (FTA) and follicular thyroid carcinoma (FTC). This study aimed to assess the diagnostic performance of metabolite enzymes using imaging mass spectrometry to distinguish FTA from FTC and determine the association between metabolite enzyme expression with thyroid follicular borderline tumor diagnosis. Air flow-assisted desorption electrospray ionization mass spectrometry imaging (AFAIDESI-MSI) was used to develop a classification model for the characteristics of thyroid follicular tumors among 24 samples. We analyzed the expression of metabolic enzyme markers in an independent validation set of 133 cases and evaluated the potential biological behavior of 19 borderline thyroid lesions. Phospholipids and fatty acids (FAs) were more abundant in FTA than in FTC (P<0.001). The metabolic enzyme panel—including FA synthase and Ca2+-independent PLA2, which are closely associated with altered metabolic pathways—was further identified in follicular thyroid tumors. The marker combination showed optimal performance in the validation group (area under the receiver operating characteristic curve, sensitivity, and specificity: 73.6%, 82.1%, 60.6%, respectively). The diagnostic strategy suggested considering a putative role of AFAIDESI-MSI in routine clinical triage for strict follow-up, with low metabolic enzyme expression combined with diagnostic in patients with a thyroid follicular borderline tumor diagnosis.