[The value of tomodensitometry in the diagnosis of dermoid cysts. Apropos of 5 cases].

Results of computed tomography before operation in 5 cases of dermoid cysts (mediastinal: 3; retroperitoneal: 1; ovarian: 1) are employed to assess the contribution of this technique, and to define its place in relation to other diagnostic radiological procedures (straight radiographs and ultrasonography). The CT scan enables three morphological types to be distinguished, and also supplies very precise data on the extension, limits, and relationships of the tumor. The effective place of this examination in the diagnosis of dermoid cysts depends upon two factors: data obtained from the straight radiograph and the initial site of the lesion. When the former supplies specific information, the only role of the CT scan and ultrasonography is to determine the precise extent of the tumor pre-operatively, the CT scan being superior to ultrasonography for this purpose. When straight radiographs do not reveal characteristic signs, the diagnostic assistance of the scanner appears to be irreplaceable, even in those abdominal or pelvic regions where ultrasonography is best conducted.