Increasingly small, non-palpable testicular incidentalomas <1cm are discovered in the clinical practice. The ESUR Scrotal and Penile Imaging Working Group suggests active surveillance with US, and surgery only for nodules that grow. This approach, however, requires validation.
A consecutive series of 127 incidentalomas were initially followed-up and operated if they were growing (n=28), or because of preference of the patient and of the referring urologist (n=11). For the lesions that were growing specific growth rate (SGR) and doubling time (DT) were calculated assuming an exponential grow. Also, the velocity of increase of the average diameter (∆Dav) and of the maximum diameter (∆Dmax) were calculated. Of the 127 nodules which were initially followed-up, 6 disappeared, 8 reduced in size, 85 were stable, and 28 increased in size. All 18 malignant tumours, 8/9 benign tumours, and 2/12 surgically proved non-neoplastic lesions were growing. The best cut-off values of the growth indicators to differentiate between malignant and non-malignant histology were 3.47x10-3 %volume/day, ≤179 days, >10x10-3 mm/day, and >5x10-3 mm/day for SGR, DT, ∆Dmax, ∆Dav, respectively.
A conservative approach of non-growing small incidentalomas is safe. Malignant and non-malignant small incidentalomas can be effectively differentiated based on growing parameters, even though superimposition exists.