Clinical utility of endoscopic ultrasound-guided fine-needle aspiration in mixed adenoneuroendocrine carcinoma with signet-ring cells of the pancreas: a case report and review of the literature.

ABSTRACT

A man in his 60s visited our hospital because of a pancreatic head tumor. Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) revealed that the tumor consisted of a neuroendocrine carcinoma (NEC) and adenocarcinoma, including signet-ring cell carcinoma, and that the ratio of these components was approximately 5050. Therefore, he was diagnosed with mixed adenoneuroendocrine carcinoma (MANEC). Because of liver and lymph node metastases, systemic chemotherapy was initiated using a regimen for the NEC component based on an increase in neuron-specific enolase (NSE). Although the patient achieved stable disease after two chemotherapy cycles, the tumor increased in size after three cycles, which was associated with a gradual increase in carcinoembryonic antigen and a decrease in NSE level. An EUS-FNA reexamination revealed that the adenocarcinoma component accounted for 90 % of the tumor. Thus, an adenocarcinoma chemotherapy regimen was started, and a slight reduction in tumor size was observed. Here, we report an extremely rare and remarkable case of MANEC of the pancreas that demonstrates the effectiveness of EUS-FNA for helping to decide the chemotherapy regimen.