Incidentally Discovered Hepatic Lesions

Historically, unsuspected incidental solid tumors of the liver were encountered only at the time of laparotomy when biopsy and definitive histologic diagnosis were obtainable. However, as cross-sectional imaging studies have become widely available and increasingly applied, the identification of unsuspected liver lesions has become common, and the appropriate means to address these lesions is a growing clinical problem. Although the majority of incidental liver lesions are benign and need no specific therapy, unsuspected primary hepatocellular carcinoma or metastatic tumors from a previously undiagnosed primary occur with a defined and significant frequency. It is important to recognize, however, that the range of diagnoses encountered will be related to the population under study. For example, patients subjected to imaging studies to investigate benign conditions such as cholecystitis or renal colic are likely to have findings that mirror those of the general population. By contrast, the likelihood of encountering malignant hepatic lesions will probably be greater in patients diagnosed with cancer and undergoing extent of disease assessment or in chronic hepatitis patients undergoing screening evaluation. Thus, the radiographic findings and the clinical context must always be considered together to formulate an appropriate differential diagnosis. In many cases, a precise diagnosis of an incidental liver lesion can be made on the basis of the 2