Unusually large anterior fontanellar bone and diffuse capillary malformation with overgrowth in a three-month-old child - a computed tomography case report

Wormian Bone in the Anterior Fontanelle of an Otherwise Well Neonate

Wormian bones are supernumerary bones of the skull that form as a result of extra-ossification centers during development in utero. They are a common finding that typically lie within and are surrounded by suture lines, especially the lambdoidal and coronal sutures. Wormian bones located within the fontanelles of neonates have a lower reported incidence and have been associated with various disorders such as craniosynostosis and osteogenesis imperfecta. Few reports have documented the existence of a Wormian bone in the fontanelle of an infant without complications or underlying pathology. There are limited resources or case reports that discuss a Wormian bone as a variant of normal. This report details the case of a child with an isolated Wormian bone within the anterior fontanelle discovered before discharge from hospital at birth. The child went on to have normal growth of his head circumference and did not have any further developmental complications after follow-up.

Anterior Fontanelle Wormian Bone/ Fontanellar Bone: A Review of this Rare Anomaly with Case Illustration

Wormian bones are a relatively rare skeletal anomaly that present as accessory bone(s) within the sutures of the cranium and even more rarely within the fontanelles. It is believed that they arise from the formation of abnormal cranial ossification centers. Although not extensively reported in the literature, this anomaly is thought to be associated with other anatomical anomalies such as osteogenesis imperfecta, rickets, and other bone dysplasias. When located within the fontanelles, the most likely site of occurrence is the posterior fontanelle. This case report describes a rare incidence of wormian bone within the anterior fontanelle of an infant who had concurrent craniosynostosis. More research and reporting of this anomaly is necessary to verify any correlated syndromes, and determine the underlying etiology.