Musinous cystic neoplasia mimicking hydatid cyst in the liver: Two rare cases.

Mucinous cystic neoplasm of the liver (MCN-L) is a rare tumor which accounts for less than 5% of all liver cysts. Although they are considered to be "benign cysts" radiologically and clinically because of their slow growth, they are considered as premalignant. We present two radiologically misdiagnosed cases that operated in a short time range, in order to increase awareness for these rare tumors. A 47-year-old female patient who had no active complaints 58 x 40 mm cystic lesion was detected in the liver, which was diagnosed hydatid cyst radiologically. The pathological examination showed multiloculated cysts which was covered by low-grade mucinous epithelium and ovarian-type stroma on the cyst wall. A 50-year-old female patient presented with abdominal distention. The radiographical screening revealed a 204 x 140 mm cystic lesion that completely fills left lobe of liver which interpreted in favor of hydatid cyst. Histopathologically, the inner surface of the cyst was covered with low grade mucinous epithelium. Ovarian-type stroma was detectable only by immunohistochemistry due to significant bleeding and edema on the wall. The diagnosis of both of our cases was low grade MCN-L. Since cysts were not intact at the time of gross examination, we could not make any comment about surgical margins or total excision. MCN-L is a tumor that creates difficulty in presurgical differential diagnosis because of its rarity and lack of specific radiologic features. Although the prognosis is excellent as a result of total excision in the benign group, relapses have also been reported.