Spontaneous external fistula of a hydatid liver cyst in a diabetic patient.

Background: The liver is the most common site of hydatid disease. Complications like cyst rupture and infection may occur, sites of rupture including: bile ducts, gastrointestinal tract, bronchi, peritoneal and pleural cavity. Rupture into the subcutaneous tissue followed by external fistula is an extremely rare complication.

Case Report: A 71-year-old diabetic woman was referred for a progressive growing mass in the right hypochondrium, with a central fistula draining clear liquid with cystic elements and white membranes. No history of fever or jaundice was present. Abdominal ultrasound (followed by CT scan) revealed a liver hydatid cyst in the right lobe, in contact with the anterior abdominal wall, and a parietal fistula track. Cystic fluid exam showed protoscolices and serological ELISA test was positive for hydatid disease. At surgery, the lesion was approached through an incision starting from the fistula site. Partial cystectomy and external drainage of the residual cavity were performed. The fistula track was totally resected. After an uneventful recovery and six months of anti - parasitic treatment, the patient is symptoms- free (3 years after surgery).

Conclusions: Spontaneous cyst-cutaneous fistula is an extremely rare complication of hydatid liver cyst, usually occurring silently, in elder people. Surgery is required to achieve complete evacuation of the cyst contents and resolution of the residual cavity. To the best of our knowledge, this is the seventh case published, and the first one in the Romanian literature.