Precocious puberty related to Leydig cell testicular tumor: the diagnostic imaging keys

Background We report the challenging case of a 6-year-old boy with precocious puberty related to histologically proven Leydig cell tumor. Case presentation Multiparametric ultrasound and magnetic resonance imaging (MRI) was performed. Interesting findings were scarcely or never reported in children and differed from adults Leydig cell tumors s such as the hyperechogenic halo surrounding the lesion and the dominant central vascularization using ultrasensitive Doppler. MRI revealed an enlarged testicle with strong enhancement of a tumor, a tumor apparent diffusion coefficient (ADC) of 600 × 10 −3 mm 2 /s and a lower ADC value of the non-tumor parenchyma compared to the contralateral testis (ADC = 800 × 10 −3 mm 2 /s vs 1100 × 10 −3 mm 2 /s), attributed to the spermatogenesis induced by hormonal impregnation. Conclusion We illustrate multiparametric US and MRI findings of a pediatric Leydig cell tumor, including the imaging changes attributed to local hormone secretion, which may be helpful in similar cases.