title: An Oncocytic Variant of Intraductal Papillary Neoplasm of the Bile Duct that Formed a Giant Hepatic Cyst.
abstract: 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 (18)F-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.
authors.affiliation: Department of General Surgical Science, Gunma University Graduate School of Medicine.
authors.forename: Akira
authors.initials: A
authors.lastname: Watanabe
authors.forename: Hideki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Norio
authors.initials: N
authors.lastname: Kubo
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Araki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Sasaki
authors.forename: Wataru
authors.initials: W
authors.lastname: Wada
authors.forename: Hideo
authors.initials: H
authors.lastname: Arai
authors.forename: Kazuha
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Shinji
authors.initials: S
authors.lastname: Sakurai
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kuwano
keywords: FDG-PET; IPNB; hepatic cyst; oncocytic variant