Prospective Evaluation of 18F-PSMA-1007 PET/CT in Renal Masses Paired with PSMA Immunohistochemistry.

Background Incidental RM are increasingly detected with cross-sectional imaging, and 20–30% of resected small RM are benign, exposing patients to potentially unnecessary surgery. Improved preoperative characterization is needed. PSMA expression in tumor neovasculature enables functional assessment, and ¹⁸ F-PSMA-1007 has lower renal elimination than ⁶⁸ Ga-PSMA-11, potentially improving lesion conspicuity and cost-effectiveness. Methods Prospective cross-sectional accuracy study including 24 adults with renal masses scheduled for nephrectomy. All underwent ¹⁸ F-PSMA-1007 PET/CT ~ 60 minutes post-injection. PET positivity was defined as uptake greater than splenic SUV or clear qualitative uptake. PSMA immunohistochemistry in tumor vasculature was graded as absent, mild, moderate, or marked. Results Twenty-five RM were analyzed (24 patients), all incidentalomas: 14 (56%) RCC—10 clear cell, 3 papillary, 1 chromophobe—and 11 (44%) benign. PET detected 10/14 RCC (sensitivity 71.4%) with specificity 54.5% for malignant versus benign discrimination; sensitivity was higher in clear cell (80%) than papillary RCC (33.3%). PET uptake correlated with PSMA expression on IHC (p = 0.026). Mass size showed a linear association with PSMA expression; all lesions > 30 mm expressed PSMA, with marked expression in 54.5% versus 7.7% of lesions ≤ 30 mm. Conclusion ¹⁸ F-PSMA-1007 PET/CT is a promising adjunct for RM evaluation, reflecting angiogenic activity and performing best in clear cell RCC. Despite modest overall malignant–benign discrimination, PSMA expression increased with tumor size, especially above 30 mm. Larger, longitudinal studies are warranted.