The prognosis of pediatric adrenocortical carcinoma often depends on prompt diagnosis to begin treatment before metastatic progression. We discuss a girl who presented at 8 months of age with virilization, which was thought to be due to exposure to a topical testosterone preparation being used by her father. Her testosterone level did not decrease promptly after her father discontinued the medication, however, and when she followed up with signs of Cushing syndrome 5 months later, metastatic adrenocortical carcinoma was diagnosed. The patient was successfully treated with surgery and multiagent chemotherapy. Nine months after the end of treatment, her testosterone level was again found to be elevated. Testosterone precursors were now absent, however, and there were no imaging signs of recurrence. Further history showed that her father had restarted topical testosterone, and this time, exogenous exposure was correctly diagnosed. As use of topical testosterone becomes more prevalent, exogenous exposure must be considered in the differential diagnosis of childhood virilization. Any persistent testosterone elevation after exposure ceases or signs of hypercortisolism, however, are inconsistent with this diagnosis. We believe that the risk-benefit ratio favors abdominal ultrasound to rule out malignancy in all children presenting with virilization.