[An infant with a cranial swelling: sub-aponeurotic fluid collection].

A sub-aponeurotic fluid collection (an extracranial fluid accumulation between the galea aponeurotica and the periostium of the scalp) of 2 week duration was observed in a 2.5-month-old male infant. In contrast to a subgaleal bleeding, which occurs on the first day after birth and is of a progressive nature, swelling caused by sub-aponeurotic fluid collection does not occur until a few weeks after birth and shows a benign course. The exact etiological mechanism of this fluid collection is unknown. It is probable that temporary (micro) fluid fistula, as a result of birth trauma, plays a role. Management is conservative, and complete reabsorption can be expected within a few weeks to months at the most.