Solitary non-parasitic liver cysts are being increasingly diagnosed due to the increased use of abdominal sonography. The majority of solitary liver cysts are asymptomatic; however, there are some complications which include infection, perforation, spontaneous hemorrhage, obstructive jaundice and neoplastic degeneration. In some cases a cystic liver lesion may mimic a tumor and is difficult to differentiate with standard imaging studies or fine needle aspiration cytology. Here in, we report a case of adenocarcinoma arising in a solitary hepatic cyst complicated with Klebsiella pneumoniae infection. High levels of CEA in the cyst fluid levels suggested malignancy, which was confirmed by pathology of the resected specimen. Solitary non-parasitic liver cysts are being increasingly diagnosed due to the increased use of abdominal sonography. However, there are some complications which include infection, perforation, spontaneous hemorrhage, obstructive jaundice and neoplastic degeneration. In some cases a cystic liver lesion may mimic a tumor and is difficult to differentiate with standard imaging studies or fine needle aspiration cytology. Here in, we report a case of adenocarcinoma arising in a solitary hepatic cyst complicated with Klebsiella pneumoniae infection. High levels of CEA in the cyst fluid levels suggested malignancy, which was confirmed by pathology of the resected specimen.