Intraductal oncocytic papillary neoplasm: a benign hepatic cystic neoplasm

Abstract

A 61-year-old Asian man presented with severe right upper quadrant pain which had been worsening for several months. Laboratory results indicated elevated aspartate aminotransferase and alanine aminotransferase. The subsequent ultrasound, CT and MRI showed a large cystic mass with solid components and severe intrahepatic and extrahepatic biliary ductal dilatation. The mass was resected and pathology showed a well-demarcated mucinous cystic lesion with polygonal cells containing ovoid nuclei and abundant pink oncocytic cytoplasm. These findings are characteristic of intraductal oncocytic papillary neoplasm (IOPN), a rare subtype of intraductal papillary neoplasm of the liver. IOPN occurs most frequently in the Asian regions endemic to clonorchiasis and hepatolithiasis; however, cases have been reported in the Western world as well. Patients with IOPN are male or female and typically middle-aged. Treatment is typically resection. Prognosis is favourable and recurrence is rare. The 5-year survival rate is upwards of 80%.

Keywords: Gastroenterology; Liver disease; Radiology.

Figure 1

CT of the abdomen and pelvis with intravenous contrast. Coronal image shows a large cystic lesion with multiple enhancing solid papillary soft tissue projections. Although there is mild intrahepatic ductal dilatation of the left lobe of the liver, the liver parenchyma is grossly normal.

Figure 2

CT of the abdomen and pelvis with intravenous contrast. Axial image of the inferior aspect of the right lobe of the liver shows dilated intrahepatic duct. The dilated ducts were found to contain mucin intraoperatively.

Figure 3

Axial T1 postcontrast image with fat suppression shows multiple solid papillary projections.

Figure 4

Right lobe of the liver (partial hepatectomy) received fragmented, measuring 22.0 cm in maximum dimension. A clearly demarcated cystic lesion is composed of friable tan-pink papillary projections.

Figure 5

Low-power morphology demonstrates a homogeneous papillary architectural pattern throughout.

Figure 6

Medium-power morphology demonstrates abundant papillae with fibrovascular cores present as an intraductal proliferation, well-circumscribed and separated from non-neoplastic liver.

Figure 7

High-power cytomorphology demonstrates regular round-ovoid nuclei with conspicuous nucleoli. The cells are polygonal/epithelioid with abundant pink oncocytic granular cytoplasm. Extracellular clear mucoid fluid was seen elsewhere on high power between the layers of oncocytic cells.