Clinical evaluation of 2-(¹⁸F) fluoro-2 deoxy-D-glucose PET/ CT in hereditary leiomyomatosis and renal cell carcinoma.

383 Background: 2-(18F) fluoro-2 deoxy-D-glucose (FDG) PET/CT is a useful tool in the staging of malignancies. In patients with kidney cancer, the role of FDG is limited in those with clear-cell histology and remains to be evaluated with other subtypes. Kidney cancer associated with hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is characterized by a defect in the Krebs cycle rendering these tumors highly dependent on aerobic glycolysis (the ‘Warburg effect’) with high glucose uptake to fulfill their energy requirements; we hypothesized that FDG PET/CT may have excellent sensitivity for staging in this condition. Methods: We retrospectively reviewed patients with HLRCC kidney cancer that underwent FDG PET/CT in conjunction with anatomic imaging at our institution. The ability of FDG PET/CT to detect malignant lesions (defined using pathologic or radiologic criteria) was evaluated. Results: A total of 30 patients underwent 42 PET /CTs. Conventional imaging identified a total of 107 lesions. Both patient and lesion-based analyses were performed. A total of 90 lesions, including ten renal lesions, were classified as malignant. 76 of 80 extra-renal lesions were correctly identified as malignant by PET/CT (sensitivity, 95%, CI 88-98%). In contrast, only 4 of 10 renal lesions were correctly identified as malignant (sensitivity, 40%, CI 17-69%). 11 of 12 histologically confirmed extra-renal lesions were PET avid (sensitivity, 92%, CI-64-98%). 10 of 12 (83%) benign lesions associated with HLRCC including uterine/cutaneous leiomyomas and adrenal nodules were PET avid. In a patient based analysis, all 18 patients with extra-renal spread of kidney cancer were correctly identified (sensitivity 100%, CI 82-100%). Conclusions: FDG PET/CT is a highly sensitive diagnostic modality for identifying metastatic kidney cancer associated with HLRCC. Prospective studies evaluating the utility of PET/CT imaging to characterize response to systemic therapy are currently underway.