Abstract
BackgroundMixed adenoneuroendocrine carcinoma (MANEC) of the common bile duct (CBD) is very rare, with only 10 reported cases. Here, we report a case of MANEC of the distal bile duct (DBD) that was surgically resected under a diagnosis of cholangiocarcinoma (CCA).Case presentationA 60-year-old male had epigastric pain and was admitted to our hospital for the treatment of a suspected CBD stone. Upon admission, laboratory findings revealed elevated hepatobiliary enzymes including serum aspartate aminotransferase, serum alanine aminotransferase, serum glutamyltransferase, and serum alkaline phosphatase. Both carcinoembryonic antigen and carbohydrate antigen 19-9 were negative. Computed tomography (CT) showed dilation of the CBD. Endoscopic retrograde cholangiopancreatography (ERCP) showed circumferential stenosis and a 5-mm elevated lesion in the DBD. Brush cytology showed atypical ductal cells, indicating adenocarcinoma (AC) of the DBD. Under a diagnosis of CCA of the DBD, a subtotal stomach-preserving pancreaticoduodenectomy was performed. Neither peritoneal dissemination nor lymph node metastasis was found. Microscopically, the lesion was seen to be composed of predominantly well-differentiated tubular AC in the superficial layer of the tumor, admixed with neuroendocrine carcinoma (NEC) in the deeper portion, indicating a diagnosis of MANEC of the DBD. After immunohistochemical staining, NEC components were positive for synaptophysin and CD56 and were for SSTR2, SSTR5, and mammalian target of rapamycin (mTOR). Three months postsurgery, postoperative adjuvant chemotherapy with S-1 was started. More than 3 years postsurgery, he is alive without recurrence.ConclusionsMANEC is highly malignant, progresses rapidly, and has a poor prognosis. Preoperative diagnosis is difficult; therefore, identifying NEC components by immunohistochemical staining using resected specimens is important.
Highlights
Mixed adenoneuroendocrine carcinoma (MANEC) of the common bile duct (CBD) is very rare, with only 10 reported cases
The present study reports the case of a 60-year-old male with MANEC of the distal bile duct (DBD) that was initially diagnosed and surgically resected as cholangiocarcinoma (ACC)
Postoperative adjuvant chemotherapy with S-1 (120 mg/body/day) was Discussion Neuroendocrine neoplasms (NENs) are composed a group of tumors exhibiting neuroendocrine phonotypes and are divided into three main categories according to the 2010 World Health Organization classification system: well-differentiated neuroendocrine tumors (NETs); grade 1 and 2, Ki-67 ≤ 20% and/or mitotic count ≤ 20 per 10 high-power fields, poorly differentiated NECs; and grade 3, Ki-67 > 20% and/or mitotic count > 20 per 10 high-power fields and MANECs [11]
Summary
We presented the case of a 60-year-old male with MANEC of the DBD. Most MANEC cases, including this one, are initially diagnosed as CCA. Because MANEC may show more aggressive behavior and have a poor prognosis, it may be important to identify the NEC component using immunohistochemical staining with neuroendocrine markers for correct diagnosis and choice of treatment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
