Hypovascular hepatocellular carcinoma undetected at angiography and CT with iodized oil.

Eighteen patients with 22 hepatocellular carcinoma (HCC) lesions less than 2 cm in diameter were examined with conventional angiography, digital subtraction angiography (DSA), and computed tomography (CT) after intraarterial injection of iodized oil (Lipiodol CT). Eight lesions detected at ultrasound examination of eight patients were not identified at conventional angiography, DSA, or Lipiodol CT. At histologic examination, all eight lesions were found to consist of well-differentiated carcinoma of grade I or II on the Edmondson-Steiner scale, and four had fatty change in cancer cells. Percutaneous tissue-core biopsy was indispensable in the diagnosis of well-differentiated HCC lesions that could not be diagnosed with conventional angiography, DSA, and Lipiodol CT.