Intraductal oncocytic papillary neoplasm of the bile duct: ultrasonography and CT findings with pathological correlations

Intraductal oncocytic papillary neoplasm: a benign hepatic cystic neoplasm

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%.

Bile duct adenoma with oncocytic features

Bile duct adenomas are benign bile duct proliferations usually encountered as an incidental finding. Oncocytic bile duct neoplasms are rare and the majority are malignant. A 61-year-old male with a diagnosis of colorectal adenocarcinoma was undergoing surgery when a small white nodule was discovered on the surface of the right lobe of his liver. This lesion was composed of cytologically bland cells arranged in tightly packed glands. These cells were immunopositive for cytokeratin 7, negative for Hep Par 1, contained mucin, and had a Ki67 proliferation index of 8%. The morphology, immunophenotype, presence of mucin, and normal appearing bile ducts, as well as the increased Ki67 proliferation rate, were consistent with a bile duct adenoma with oxyphilic (oncocytic) change. Oncocytic tumors in the liver are rare; the first described in 1992. Only two bile duct adenomas with oncocytic change have been reported and neither of them had reported mucin production or the presence of normal appearing bile ducts within the lesion.

An Oncocytic Variant of Intraductal Papillary Neoplasm of the Bile Duct that Formed a Giant Hepatic Cyst

Intraductal papillary neoplasms of the bile duct (IPNB) is the collective term used to refer to papillary bile duct tumors, mucin producing bile duct tumors, and cystic bile duct tumors. Pathologically, these tumors may be considered a highly differentiated adenocarcinoma or a tumor of borderline malignant potential. IPNB is classified into one of four variants based on cell differentiation. The rarest, oncocytic, is characterized by oxyphilic granular cytoplasm and no mucous cell differentiation. The patient, a 59-year old man, was admitted with a complaint of abdominal fullness and a 30×25 cm cystic mass in the right hepatic lobe demonstrated on computed tomography (CT). The mass had no malignant features on CT or magnetic resonance imaging; however, a portion was FDG avid on ¹⁸F-fluorodeoxyglucose positron emission tomography scan (FDG-PET). A fenestration operation was performed for the presumed diagnosis of a hepatic cyst. Pathological examination of the cyst contents demonstrated some atypical cells suspicious for malignancy. After eight months of observation, abnormal FDG uptake was again observed at the residual cyst. A partial hepatectomy was performed to excise the cyst. Pathological examination demonstrated adenocarcinoma in situ derived from an oncocytic IPNB variant. Following the resection, the patient remained disease free for 40 months. This is an extremely rare case of an oncocytic variant of IPNB that was difficult to distinguish clinically from a solitary hepatic cyst.

Intraductal oncocytic papillary neoplasm of the extrahepatic bile duct: report of a case

We report a rare case of an intraductal oncocytic papillary neoplasm (IOPN) of the extrahepatic bile duct. A 66-year-old man was admitted to our hospital for investigation of right-sided back pain. Ultrasonography, computed tomography and magnetic resonance imaging showed a papillary lesion, 3 cm in diameter, in the middle bile duct, invaginating into the cystic duct. We made a provisional diagnosis of middle bile duct cancer and performed substomach-preserving pancreatoduodenectomy. Macroscopically, the middle bile duct contained a two-humped papillary tumor, one tip of which invaginated into the cystic duct. Microscopically, the tumor consisted of cuboidal cells with abundant eosinophilic cytoplasm resembling that of oncocytes and a fine fibrovascular core. The tumor cells were stained strongly with antimitochondria antibody. Based on these findings, the tumor was diagnosed histologically as IOPN of the extrahepatic bile duct. The patient died of prostate cancer 51 months after surgery, but without evidence of recurrence of the IOPN.

Intraductal oncocytic papillary neoplasms of the pancreas and bile ducts: a description of five new cases and review based on a systematic survey of the literature

BACKGROUND

Intraductal oncocytic papillary neoplasms (IOPN) are rare tumors of the pancreatic and biliary ductal system. It is not absolutely clear if the molecular and clinicopathologic characteristics of IOPN differ significantly from other related lesions, namely intraductal papillary mucinous neoplasms (IPMN). Therefore it is not clear if it is reasonable to consider IOPN as a separate diagnostic and clinical entity.

METHODS

In order to describe the clinicopathologic characteristics of IOPN and to compare them with the IPMN profile, we performed a systematic review of the literature and additionally studied five previously unreported IOPN cases.

RESULTS

IOPN differ from IPMN by lack of K-ras gene mutations in all studied cases. Several differences in the clinical and biological profile between IOPN and IPMN exist, but they are of quantitative rather than of qualitative nature. Additionally, pancreaticobiliary or gastric-foveolar IPMN components may coexist with IOPN component within a single lesion, which suggests at least a partial relation of the pathogenetic pathways of IPMN and IOPN. Importantly, the pathogenesis of accumulation of mitochondria and oxyphilic appearance of IOPN remains unknown.

CONCLUSIONS

At present, there are no reliable criteria other than histopathological picture and K-ras gene status to differentiate IOPN from IPMN. In particular, no clear differences in optimal treatment options and prognosis between these tumors are known. Further studies are needed to clarify the biology of IOPN and to establish their position in clinicopathologic classifications of pancreatic tumors.