An insulin-producing teratoma of the mediastinum was found in a 5-year-old boy. Asymptomatic hypoglycemia and an elevated plasma level of immunoreactive insulin were noted preoperatively. After removal of the teratoma, which contained an abundance of islet cell tissue, both of these values returned to normal. This is, to our knowledge, the first report of a benign teratoma with such endocrine activity.
Honicky RE, dePapp EW. Mediastinal Teratoma With Endocrine Function. Am J Dis Child. 1973;126(5):650-653. doi:10.1001/archpedi.1973.02110190522012