Participants in the study will be randomized to one of two treatment groups, receiving either testosterone undecanoate (low-dose androgen) or placebo, for two 6 months. All participants will be evaluated for safety at the beginning of the study and at 2, 4, and 6 months with careful history, physical examination, blood sampling and testicular ultrasonography. Patients will also be offered the possibility to perform Magnetic Resonance Imaging (MRI) of the testis at baseline and after treatment, and/or surgical enucleation of the lesions.