Case report: Diagnostic value of [99mTc]Tc-sestamibi SPECT/CT in a very small renal mass: a histopathology-matched case

A 12-mm enhancing renal mass was incidentally detected in a 61-year-old man during CT urography. To refine characterization, [ 99m Tc]Tc-sestamibi SPECT/CT was performed, showing radiotracer uptake comparable to the surrounding cortex (L/K ratio 0.95) despite the sub-centimetric size, suggestive of an oncocytic or otherwise indolent lesion. Given patient-specific factors and contralateral renal impairment, partial nephrectomy was undertaken, revealing a renal oncocytoma with typical histopathological and immunohistochemical features. This case highlights that, although technical limitations exist for lesions <2 cm, [ 99m Tc]Tc-sestamibi SPECT/CT may still provide interpretable molecular information in selected very small renal masses, especially when integrated with CAIX-targeted radiotracers – such as girentuximab – whose complementary biological profile enhances noninvasive renal mass assessment. The concordance between imaging and histology supports further investigation into standardized acquisition and interpretation criteria to optimize noninvasive assessment and guide management of small renal masses.