Fetal kleeblattschädel cranium: morphologic, radiographic, and histologic analysis

The kleeblattschädel deformity is a rare craniofacial condition typified by its trilobed, cloverleaf skull. The pathophysiology of this process is controversial. The morphologic, radiographic, and histologic abnormalities identified in the cranial base of an 18-gestational-week fetus with kleeblattschädel skull have not been described previously. Recently, the intrauterine diagnosis of kleeblattschädel was established by serial ultrasonography and, based on this evidence, the fetus was aborted. The fetus was studied extensively. Standard radiographs and high-resolution CT scans were obtained. Three-dimensional, reformatted contour surface images were constructed from the CT scan data. The cranial base was examined grossly, radiographically, and histologically. Histologic microanatomic study concentrated on structures of the mid-sagittal cranial base from the occiput to the mid maxilla. The distorted cranial architecture in kleeblattschädel deformity has, in the past, been attributed largely to the cranial base deformity which secondarily distorts the developing brain. Our study, however, suggests that the calvarium itself may be the primary focus of abnormal events leading to synostosis. The findings in this study seem to be inconsistent with earlier theories about the abnormal development of craniodysostoses.