Consensus guidelines for radiological diagnosis of hepatocellular carcinoma (HCC) have been drafted by several large international working groups. This article reviews the similarities and differences between the most recent guidelines proposed by the American Association for Study of Liver Diseases and the Asian Pacific Association for the Study of the Liver. Current evidence for the various imaging modalities for diagnosis of HCC and their relevance to the consensus guidelines are reviewed.

Hepatocellular carcinoma (HCC) is increasingly being detected at an earlier stage, owing to the screening programs and regular imaging follow-up in high-risk populations. Small HCCs still pose diagnostic challenges on imaging due to decreased sensitivity and increased frequency of atypical features. Differentiating early HCC from premalignant or benign nodules is important as management differs and has implications on both the quality of life and the overall survival for the patients. Gadoxetate acid (Gd-EOB-DTPA, Primovist®, Bayer Schering Pharma) is a relatively new, safe and well-tolerated liver-specific contrast agent for magnetic resonance (MR) imaging of the liver that has combined perfusion- and hepatocyte-specific properties, allowing for the acquisition of both dynamic and hepatobiliary phase images. Its high biliary uptake and excretion improves lesion detection and characterization by increasing liver-to-lesion conspicuity in the added hepatobiliary phase imaging. To date, gadoxetate acid-enhanced MRI has been mostly shown to be superior to unenhanced MRI, computed tomography, and other types of contrast agents in the detection and characterization of liver lesions. This review article focuses on the evolving role of gadoxetate acid in the characterization of HCC, differentiating it from other mimickers of HCC.

A 71-year-old man presented to our hospital with 3-week history of fever in the background of loss of both weight and appetite over the past 3 months. He was found to have a large 10-cm mass in the right lobe of the liver on a triple-phase computed tomographic scan. The tumor showed a distinct fatty component, with areas of arterial enhancement and venous washout suggestive of hepatocellular carcinoma (HCC), another component showing progressive and late enhancement suggestive of cholangiocarcinoma (CC), and a third component showing persistent hypoenhancement relative to the liver parenchyma. He underwent surgical resection. This was histopathologically a biphasic tumor composed of areas showing hepatocytic differentiation, in contiguity with areas showing infiltrative glands set within fibrous stroma in keeping with combined hepatocellular and cholangiocarcinoma (cHCC-CC). A third component of pleomorphic spindle and epithelioid appearance in keeping with sarcomatous transformation was also found intimately related to the CC component. The patient developed extensive thoracic and abdominal metastases 2 months after surgery and died shortly after.

Our early experience has shown that CEUS can be accurate in differentiating malignant from benign FLLs and may become a useful first-line imaging tool where CT or MRI are not available or contra-indicated.

A 69-year-old man presented with intestinal obstruction and peritonism. Chest and abdominal X-rays showed massive pneumoperitoneum with large bowel obstruction (Figs. 1, 2). Exploratory laparotomy revealed closed loop obstruction secondary to sigmoid volvulus with extensive pneumatosis cystoids intestinalis of non-dilated small bowel (Figs. 3, 4), without evidence of perforation. We postulate that rupture of a submucosal cyst in the small bowel resulted in pneumoperitoneum. Total colectomy was performed, with ileocecal anastomosis and defunctioning ileostomy. Histology confirmed pneumatosis cystoides intestinalis of small bowel without full-thickness perforation (Figs. 5, 6).Singapore General Hospital, Singapore, Singapore e-mail: eu.kong.weng@sgh.com.sg