Shunt malfunction mimicking a cystic tumour.

Shunt malfunction represents one of the most common problem to deal with in the daily neurosurgical practice. Among the variety of possible presentations, the cyst-like dilatation of the brain around the proximal catheter is one of the most rare and misleading type. The case of a boy with a 'tumour-like' proximal shunt malfunction is described and the pertinent literature is analysed.