Prenatal sonographic features of embryonal rhabdomyosarcoma.

We describe a case of fetal rhabdomyosarcoma detected during the third trimester of pregnancy by prenatal sonography. At 33 weeks' gestation, sonography performed because of suspected polyhydramnios showed a solid mass of 120 x 54 mm arising from the anterior wall of the fetal thoracic cage. Another mass within the left maxillary area which originated from the left orbital floor was also detected. In the abdomen, there were multiple round masses in and around the liver. As the previous scan at 28 weeks had appeared normal, the multiple masses which became visible and enlarged rapidly in different locations led us to believe that there was fetal cancer. The most likely diagnosis was rhabdomyosarcoma (which was later confirmed), because it is the most prevalent soft-tissue tumor in children and may develop within or outside muscle anywhere in the body and at any age. Two other reported cases which were detected by prenatal ultrasound examination are also discussed.