Hydatid cyst of bone.

Hydatid disease is an extremely uncommon differential diagnosis in the cystic/lytic lesions of bone. We present a rare case of echinococcal infection of femur which presented as pathological fracture in a middle-aged female and diagnosis was confirmed by histopathology. Hydatid disease of bone is often asymptomatic, and its diagnosis is usually made when lesions have become extensive.