Barnes Jewish Hospital/Washington University School of Medicine
Introduction: Benign renal masses are challenging to differentiate from malignant renal masses using noninvasive techniques. 99m Tc-sestamibi scan single photon emission computed tomography/computed tomography (sestamibi scan) has emerged as a potential diagnostic tool. Already widely utilized in the diagnosis of hyperparathyroidism, sestamibi scans differentiate renal masses on the basis of differences in mitochondrial content between malignant renal masses and oncocytomas. This study sets out to evaluate the concordance between renal mass sestamibi scan interpretation and surgical pathology.
Methods: We retrospectively identified patients undergoing sestamibi scan and renal mass biopsy or excision between September 2016 and May 2021 at our institution. The sestamibi scan final diagnostic report and surgical pathology results were compared. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated.
Results: We identified 26 patients with 31 tumors. The average age of patients was 65.7 years. Sestamibi scan identified 7 oncocytomas, 20 renal cell carcinomas, and 4 mixed tumors with average size 4.8 cm, 3.2 cm, and 4.9 cm, respectively. Surgical pathology from 12 renal mass biopsies and 19 renal mass excisions showed 8 oncocytomas, 22 renal cell carcinomas, and 1 angiomyolipoma. Sestamibi scan overall accuracy was 61.3% with sensitivity 70.8%, specificity 28.6%, positive predictive value 77.3%, and negative predictive value 22.2% (Table 1).
Conclusions: Previous studies have shown that as many as 20-30% of excised renal masses are benign, calling attention to the need for improved diagnostic techniques. While the overall accuracy of sestamibi scans was moderate, positive predictive value was the highest at 77.3%. This study demonstrates that sestamibi scans can be a useful noninvasive adjunct to differentiate between benign and malignant renal masses.
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.jpg "Shilpa P. Argade, MD photo")
