Hepatic intraductal oncocytic papillary neoplasm masquerading as a hemangioma: a case report

Abstract

Objective: Intraductal oncocytic papillary neoplasm (IOPN) of the liver is a rare morphological variant of intraductal papillary mucinous neoplasm (IPMN) with malignant potential. To the base of our knowledge, less than 10 cases of hepatic IOPN have been reported. Methods: The authors present a case of a symptomatic 51-year-old male with a CT and MRI findings of a 4.4 × 3.7×4 cm lesion in the left liver compatible with a hemangioma. A follow up CT after 3 months showed increase in size of the lesion to 4.4 × 4×4 cm. Tumor markers were within normal limits. Results: Patient underwent a left lateral sectionectomy. Final pathology revealed a 5 × 4×2.5 cm cyst filled with mucinous material. Microscopic examination showed multilocular cystically dilated ducts with an intraductal arborizing complex papillary proliferation (Image 1). The lining of the epithelium was oncocytic with intracytoplasmic mucinous vacuoles in some areas (Image 2). There was focal extravasated mucin within the stroma and associated stromal reaction without evidence of stromal invasion. A final pathologic diagnosis was IOPN of the liver with high grade dysplasia. Conclusion: The patient recovered well after surgery. The oncocytic variant can be distinguished from biliary cystadenoma and cystadenocarcinoma by the lack of ovarian stroma and presence of prominent oncocytic epithelium. Although most reported cases of IOPN usually result in a benign course following resection, 2 deaths have been described due to progression of IOPN to oncocytic biliary cystadenocarcinoma with associated peritoneal dissemination. This shows the need for consideration of IOPN in the differential of liver cystic lesion, and for surgical intervention.Image 2A high-power image showing oncocytic epithelium with punched out mucin vacuoles (purple arrow) lining individual papillae.View Large Image Figure ViewerDownload Hi-res image Download (PPT)