Diaphyseal Paget's disease: an unusual finding in the tibia.

Paget's disease may present in the tibia without involvement of either end of the bone. Such unusual diaphyseal lesions are invariably lytic and, rarely, may be multifocal. They almost always involve the anterior cortex of the bone and usually have a characteristic 'V-shaped' margin at one or both ends. Expansion of the bone is common. This unusual appearance is frequently an early manifestation of the disease under the age of 40 years. Awareness of this appearance is important in order to prevent incorrect diagnosis and unnecessary biopsy or surgery.