Prevalence and importance of small hepatic lesions found at CT in patients with cancer

PURPOSE: To assess the prevalence of small hepatic lesions discovered at computed tomography (CT) in patients with cancer and to determine the frequency with which they represent clinically important findings. MATERIALS AND METHODS: The authors reviewed the CT reports obtained in 2,978 patients with cancer during a 24-month period. Small hepatic lesions (lesions 1 cm or less in diameter or deemed too small to characterize by the interpreting radiologist) noted on the initial scan were assessed at follow-up CT. The number and type of any other intrahepatic lesion, the histologic type of the primary tumor, and the presence of extrahepatic metastatic disease were also recorded. RESULTS: Small hepatic lesions were reported in 378 (12.7%) patients; 15 (4.0%) of these patients also reportedly had other larger hepatic lesions that were interpreted as metastases. Small hepatic lesions demonstrated interval growth in 44 (11.6%) patients and were therefore considered metastatic. Small hepatic lesions in 303 (80.2%) patients demonstrated no interval growth (mean follow-up, 25.6 months; range, 6-56 months) ans were therefore presumed benign. Small hepatic lesions in 31 (8.2%) patients were stable at follow-up of less than 6 months and were considered indeterminate. Among the three most common tumors (lymphoma and colorectal and breast cancers), small hepatic lesions were metastatic in 4%, 14%, and 22%, respectively. CONCLUSION: Although small hepatic lesions in patients with cancer more frequently are benign than malignant, these lesions represent metastases in 11.6% of patients.