The specificity of ultrasound in the detection of fetal intracranial tumors

Aims: To evaluate the specificity of ultrasound in identifying fetal brain neoplasms and its accuracy in the diagnosis of the tumor's histological typ e. Methods: A retrospective evaluation of 7 cases of fetal brain tumors occurr ed at our unit in the period between January 92 and June 98 has been perfor med. All prenatal ultrasonographic diagnoses were compared with the postnat al findings on the aborted fetuses (post-mortem examination) or on the newb orns (MRI or post-mortem examination). Results: In 6 out of 7 cases the antenatal ultrasonographic diagnosis of br ain tumor was confirmed postnatally, in one case a supratentorial arachnoid cyst was mistaken for a teratoma with cystic components (86 % specificity in the diagnosis of congenital brain neoplasms). Out of the 6 cases of susp ected teratomas, one revealed to be a glioblastoma, one an arachnoid cyst a nd one a primitive neuroectodermal tumor. The prenatal diagnosis was confir med in the case of choroid plexus papilloma. Prenatal ultrasonography was a ccurate in identifying the tumor's histological type in the 57 % of the cas es. The diagnoses were not modified by the transvaginal scans performed in 2 cases. Conclusions: Prenatal ultrasonography is a useful tool to identify any intr acranial space-occupying lesion larger than 10 mm. In the present study it has shown an 86 % specificity in the diagnosis of brain neoplasms. However the accuracy of ultrasound in diagnosing the tumor's histological type was limited (57 %).