Rapidly growing mature teratoma of the mediastinum: do sex hormones affect growth of the tumor?

The case of a 12-year-old girl with an anterior mediastinal tumor is reported. A mass grew rapidly and occupied the anterior mediastinum after menarche. Resected material was diagnosed as a mature teratoma. Both estrogen receptors and progesterone receptors were detected in the resected tissue. The titer of estrogen receptors was 2-11.3 femtomoles per milligram of protein and that of progesterone receptors was 9.5-15.7 fmol/mg protein. Based on these data, it was surmised that sex hormones may affect the growth of the tumor in this case. The change in sex hormones after menarche may have played a role in the rapid growth of this tumor.