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. On laparotomy there were multiple cysts seen in the residual right lobe of the liver and inflammatory changes in the abdominal wall with an external fistulous opening. Right-lobe hepatectomy was carried out along with excision of the fistulous tract. The specimen showed multiple degenerated contents of the cyst with numerous daughter cysts along the fistulous tract and examination of cyst fluid demonstrated protoscolices. The postoperative period was uneventful. He was regularly followed and was doing well.