Unusual presentation of hydatid disease.

Hydatid disease is endemic in most areas in Iran where sheep are raised, and diagnosis is fairly easy in a majority of cases. However, this fairly common disease may become very difficult and even impossible to diagnose. The most important factor in diagnosing hydatid disease is the awareness of its possibility. The striking clinical resemblance between hydatid disease and malignant diseases of some organs makes the correct diagnosis essential. In countries where this disease is endemic, any growing mass or tumor should arouse suspicion of hydatid disease.