Large parietal midline defect with unusual ridge-like structure at the rim and persistent falcine sinus

Abstract

Midline cranial defects can be divided into lesions with intracranial tissue herniation (cranium bifidum cysticum) and lesions mainly with ossification failure (cranium bifidum occultum). Herniated cephaloceles mostly require surgical resection, while persisted parietal foramina might become smaller with age. Here, we report a neonate with large symmetric midline skull defect at high parietal area. A mild bulging mass was noticed. Interestingly, unlike sac herniation, it was surrounded by bony ridges extended from the rim of the calvarial defect, which suggests aberrant ossification. Persistent falcine sinus was also detected. At the corrected age of 11months, the size of the skull defect had decreased spontaneously, favoring the diagnosis of parietal bone ossification defect. Potential mechanisms resulting in the special appearance of skull bone were discussed. Incomplete closing of the parietal foramina might be expected due to the aberrant ridge formation. We suggest protective measures for the calvarial defect.