Explosive growth of a renal tumor during active surveillance.

The incidence of small renal masses (≤ 4 cm) has increased over the past three decades. Partial nephrectomy remains the standard for treatment of such lesions, but increased attention is being given to patients who may benefit from active surveillance, given the low risk of metastatic spread and traditionally slow growth rates. Patients with significant comorbidities and the elderly are often considered optimal candidates for surveillance. We present an 86-year-old female undergoing active surveillance for a 1.4 cm lesion that grew in diameter approximately 0.5 cm per year over 3 years, followed by explosive growth to 7 cm in diameter with a retrohepatic inferior vena cava (IVC) thrombus over the subsequent 13 months.