DESCRIPTIONChildren with hydrocephalus are commonly treated with a ventriculoperitoneal (VP) shunt for diversion of CSF. Unfortunately, complications arising from VP shunting are not uncommon. Apart from shunt blockage and infection, it may become disconnected or fractured and migrate into the potential spaces or viscera.Here we present images of a unique complication of VP shunt in a 14-year-old boy who had a background history of congenital hydrocephalus. At the age of 13 years, he had a fracture of the right VP shunt at the mid-cervical spine level ( figure 1A) with migration of the distal portion into the abdomen. Revision of the right VP shunt was done but the previously migrated distal tube was not removed from the abdomen as the patient had no abdominal symptoms. However, 7 months later he presented with a 3 day history of left scrotal swelling and fever. On examination, the left scrotum was red, swollen and tender, with a palpable foreign body within.The abdominal radiograph ( figure 1B) and scrotal ultrasound (figure 2) show the presence of the previously fractured distal portion of the VP shunt in the left scrotum. Intraoperatively, a patent narrow inguinal canal was detected paving the tract for the migration. Successful removal of the tube by left herniotomy was performed with an uneventful recovery.VP shunt fracture and migration into the scrotum is a very rare phenomenon.1 This complication tends to occur in younger children because of the higher incidence of an unobliterated processus vaginalis and smaller volume of the peritoneal cavity.1 Figure 1 Images of the frontal (A) neck/chest and (B) abdominal radiographs. The neck/chest radiograph demonstrates the initial site of the fractured right ventriculoperitoneal (VP) shunt at the upper cervical region (arrowhead). The abdominal radiograph was taken 7 months later after the revision. The coiled distal portion of right VP shunt had migrated into the left scrotum (curved arrow). The tip of the right shunt was seen in the lower abdomen (black arrow) while the tip of the left shunt was seen in the left upper abdomen (white arrow). There was no evidence of intestinal obstruction. Right hip dislocation was also seen.

SUMMARYA 62-year-old man presented with a right-sided hemichorea-hemiballismus secondary to underlying nonketotic hyperglycaemia. This condition is recognised to have a unique finding of unilateral basal ganglia lesion, which is hyperdense on CT and hyperintense on T1-weighted MRI. The clinical course of this condition is benign and has a good prognosis with early correction of the hyperglycaemia. BACKGROUND

The patella is an uncommon site for all primary and metastatic bone tumours and primary intra-osseous tumours of the patella are very rare. A majority of the patella tumours are benign. We report a patient with a sudden onset swelling and pain of the right knee following a staircase fall. The plain radiograph showed an expansile multiseptated patella lesion and it was further assessed with an MRI. The radiological findings and the initial histopathological features from a limited sample were suggestive of a primary aneurysmal bone cyst. However, the final histopathological diagnosis from a more adequate specimen was a giant cell tumour with a secondary aneurysmal bone cyst.