Rapidly growing mature retroperitoneal teratomas.

Retroperitoneal mature teratomas are rare benign tumors, most commonly found in neonates and young adults. We report 2 cases of fast-growing retroperitoneal mature teratomas. Both patients were girls operated on before the age of 6 months. In both cases, during the delay between diagnosis and surgery, the tumors practically doubled in size every 10 days. We believe the possibility of rapid growth of these tumors implies that treatment should be conducted as soon as possible.