Leg swelling in a newborn.

A 2 week old male child was referred to the orthopaedic service with a swelling in the left tibia and associated deformity of the foot. He was born at 38 weeks by normal delivery and birth weight. There was no other significant history. On examination, there was a fusiform swelling over the antero-medial aspect of the tibial diaphysis. The overlying skin was normal with no local warmth and the mass was firm but not painful. The foot deformity was fully correctable. His ipsilateral hip and knee examination was normal. The limb lengths were equal with the remaining skeletal examination being normal. Initial radiological investigations included plain radiographs and later an MRI scan of the affected part (figs 1 and 2).