Differential diagnosis of small hepatocellular carcinoma and borderline lesions and therapeutic strategy.

Background/aims: To investigate imaging characteristics and surgical results of adenomatous hyperplasia and early-stage hepatocellular carcinoma.

Methodology: A retrospective study set in the First Department of Surgery, University of Tokushima, Japan. From 1994 to 1997, 33 patients with 55 small hepatocellular carcinomas (< or = 3 cm) and 10 borderline lesions (3 adenomatous hyperplasia, 5 atypical adenomatous hyperplasia, 2 atypical adenomatous hyperplasia with focal malignancy) were enrolled for this study. The detectability of these lesions on imaging was evaluated. Cumulative survival and disease-free survival rates were also calculated.

Results: Twenty-eight patients were incidentally diagnosed on ultrasonography during follow-up study for chronic disease. In the conventional studies, detection rates of ultrasonography, computed tomography and angiography for small hepatocellular carcinomas and borderline lesions were 76% 80%, 33% 10% and 36% 20%, respectively. Magnetic resonance imaging, intraoperative ultrasonography, helical computed tomography and portal angiographic computed tomography showed better results of 67% 20%, 100% 90%, 70% 50% and 74% 56%, respectively. On differential diagnosis, the ratio of echo level in small hepatocellular carcinomas was significantly higher than that in borderline lesions. The 3-year and 5-year survival rates for all patients were 61% and 41%, while disease-free survival rates at the corresponding times were 15% and 7%, respectively. A total of 25 patients (76%) developed intrahepatic recurrence during a mean follow-up of 33.8 months, although there was no recurrent lesion in 4 adenomatous hyperplasia patients treated with microwave coagulation therapy and ethanol injection intraoperatively.

Conclusions: For tumors larger than 1 cm in diameter, the detection rates with various diagnostic modalities were rather high. However, the differential diagnosis of borderline lesions from small hepatocellular carcinomas could be based on pathologic studies only. Early detection of small hepatic lesions and treatment by methods such as resection or ethanol injection are of critical importance in improving long-term survival.