Benign extra axial collection of infancy is a benign clinical entity characterized by rapid head enlargement in an infant with normal neurodevelopment.
We report on an infant who was referred at 3 months with rapidly increasing head circumference. The development was normal and there was a family history of macrocephaly. MRI brain showed normal ventricles with no hydrocephalus. There was significant prominence of subarachnoid space, particularly in fronto- parietal regions. Interestingly, there was moderate degree of cerebral atrophy.
Paediatricians should consider this diagnosis in any infant with rapid head enlargement and normal neurodevelopment. It is a benign condition that requires no surgical intervention because it often resolves spontaneously. The age of onset varies, but it is often seen in the first year of life, more often in boys, when an infant is noticed to have rapid head enlargement. It should not be confused with hydrocephalus or any other intracranial pathologies that are often associated with abnormal neurodevelopmental milestones. The persistence of the subarachnoid fluid collection beyond 2 years of age or a change in neurodevelopment calls for further evaluation to exclude intracranial pathology.