A case of pseudocystic liver metastases from an atypical lung carcinoid tumor

Metastatic neuroendocrine tumors of the liver typically appear as solid, hypervascular masses on imaging. Pseudocysts mimicking simple cysts are extremely rare. A 42-year-old Japanese woman was referred with a single pulmonary mass in the left lower lobe. No metastatic lesion was detected and no occupying lesion in the liver was observed. The lung tumor was diagnosed as an atypical carcinoid. Postoperative investigation revealed new hepatic simple cysts in the liver, which increased in size over time and changed into hemorrhagic cysts. Fluorodeoxyglucose positron emission tomography and somatostatin receptor scintigraphy using (111)In-octreotide demonstrated no accumulation in the liver. Our patient did not have symptoms consistent with carcinoid syndrome. The patient underwent partial resection of the cystic lesions of the liver. Gross examination of the tumors demonstrated thin-wall cavitated lesions with hemorrhage which were metastases from the atypical carcinoid of the lung. When a growing cystic lesion with intracystic hemorrhage is found in the liver of a patient with a history of carcinoid tumors, pseudocysts caused by degeneration of a carcinoid metastasis should be considered as a differential diagnosis.