{'fraction_non_alphanumeric': 0.0473328324567994, 'fraction_numerical': 0.02779864763335838, 'mean_word_length': 4.816593886462882, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Malignant intraductal oncocytic papillary neoplasm of the common bile duct.

Recently, several cases of intraductal oncocytic papillary neoplasm (IOPN) of the liver and hepatic bile ducts have been reported. The author herein reports the first case of IOPN of the common bile duct (CBD). A 78-year-old man was admitted to our hospital because of jaundice. Imaging modalities including US, CT, MRI revealed an intraductal tumor of the middle CBD and biliary dilation distal to the tumor. A partial resection of the CBD was performed. Grossly, a papillary tumor measuring 20 × 15 mm was found within the CBD. Mucus is absent. Histologically, the papillary tumor was composed of atypical oncocytes. The atypia was enough to be diagnosed as adenocarcinoma. No invasive features were noted. Immunohistochemically, the tumor cells were positive for pancytokeratins (CK), CK 7, CK 18, CK19, EMA, CA19-9, CEA, mitochondria, p53 protein, C-erbB2, Ki-67 (labeling = 80%), MUC2, MUC5AC and MUC-6,. The tumor cells were negative for CK8, CK20, chromogranin, synaptophysin, neuron-specific enolase, S100 protein, CD56, MUC1, CD10 and CDX2. These immunohistochemical findings were compatible with IOPN. The patient died of other non-tumorous disease 7 year after the operation. In summary, the author presented the first case of IOPN of the CBD.