Spontaneous external fistula: the rarest presentation of hydatid cyst.

A 65-year-old man with hydatid disease of the liver presented with a spontaneous cutaneous rupture draining about 10 L of fluid with daughter cysts. Contrast-enhanced CT showed multiple hypodense areas in the residual right lobe of the liver and abdominal wall with compensatory hypertrophy of the left lobe, confirming the diagnosis of a hydatid cyst presenting as external fistulisation which represents a very advanced stage of hydatid disease. Once the patient's nutritional status improved he was taken for surgery.