Multiparametric ultrasound for the diagnosis of Leydig cell tumours in non-palpable testicular lesions

Background: The widespread use of ultrasonography has led to an increased number of incidentally detected small non-palpable lesions, with Leydig cell tumours representing the majority of them. Objectives: The ultrasonography, real-time elastography and contrast-enhanced ultrasonography features of a large series of non-palpable testicular lesions were evaluated, focusing on the differences between Leydig cell tumours and other testicular masses. Materials and methods: Of the 4679 testicular ultrasonography examinations performed at the Authors’ Institution between January 2009 and December 2018, 78 patients (1.7%) were incidentally diagnosed with at least one non-palpable lesion and were enrolled. Thirteen patients (16.6%) declined surgery and were thus excluded. The remaining 65 underwent surgical resection with frozen section analysis. The conventional ultrasonography, colour Doppler, real-time elastography and contrast-enhanced ultrasonography were performed by a radiologist having more than 10 years of experience. Demographic and clinical data were collected. Results: Leydig cell tumours were detected in 32 patients, being the most frequent benign tumours (49.2%); of the non-Leydig cell tumours, 25 patients had malignant tumours, five non-neoplastic lesions and three other benign tumours. The Leydig cell tumour group had mostly infertility problems whereas the non-Leydig cell tumour group frequently experienced pain (p < 0.001). Leydig cell tumours were all hypoechoic (32/32, 100%; p = 0.002), more frequently presented with well-defined margins compared to non-Leydig cell tumours (30/32, 93.8% vs. 19/33, 57.6%; p = 0.001) and tended to be smaller than non-Leydig cell tumours (5.3 mm [standard deviation 2.7 mm] vs. 10.6 mm [standard deviation 3.8 mm], respectively; p < 0.001). The vascular pattern characterised by the rapid wash-in followed by the delayed wash-out observed during contrast-enhanced ultrasonography was significantly associated with the Leydig cell tumour histological diagnosis, even at multivariate analysis (odds ratio 480.5, p < 0.001), and yielded a high diagnostic accuracy (area under the receiver operating characteristic curve 0.954, 95% confidence interval 0.903–1). Discussion: Contrast-enhanced ultrasonography demonstrated high diagnostic accuracy in identifying benign testicular lesions, such as Leydig cell tumours; they are the most common non-palpable tumours detected in infertile men and may benefit from enucleation.