Pediatrics Testotoxicosis Study [Bicalutamide Anastrozole Treatment for Testotoxicosis]

Inclusion Criteria: * Provision of written informed consent of parent/legal guardian and subject assent (as needed by local requirements) * Male aged 2 years and over * Diagnosis of testotoxicosis based on the following: * Clinical features of Progressive sexual precocity documented by Tanner staging and evidence of symmetrical testicular enlargement * Clinical features of significantly advanced bone age (defined as bone age of at least 12 months beyond chronological age) * Pubertal levels of serum testosterone * Prepubertal levels of serum gonadotropins * Lack of an increase in serum gonadotropin levels following GnRH stimulation * Other pathology excluded by: * Undetectable plasma b human chorionic gonadotropin (bHCG). Samples with values below the LOQ will be reported as "\<10 IU/L" which in the clinical setting equate to 'undetectable'. * Normal levels of 17-hydroxyprogesterone (17-OHP) * Normal levels of dehydroepiandrosterone sulphate (DHEAS) * Naive to anti androgen receptor therapy: (Note: Ketoconazole and Spironolactone are considered acceptable as is prior use of anastrozole or other aromatase inhibitors) * A documented reliable height measurement taken \> 6 months prior to study enrollment. Additionally for subjects who have previously received ketoconazole or spironolactone treatment, a documented reliable height measurement taken immediately prior to beginning this treatment. (Note: for subjects who received such previous treatment only a single assessment is needed if it was taken immediately prior to beginning treatment and \> 6 months prior to study entry) * Subjects should be free of endocrine or other effects of previous treatment for testotoxicosis prior to study entry: to ensure this there should be 15 days or 4 drug half lives (whichever is the longer) washout period from prior medication for testotoxicosis. Exclusion Criteria: * Evidence of central precocious puberty as demonstrated by GnRH stimulation test * Serum concentration of total or direct bilirubin, GGT, AST or ALT greater than 1.5 times the upper limit of normal for age * Serum concentration of creatinine greater than 1.5 times the upper limit of normal for age * Any concomitant medical condition that, in the opinion of the investigator, may expose a subject to an unacceptable level of safety risk or that affects subject compliance * Known hypersensitivity to any of the study medications * Participation in a clinical study at the time of enrollment