Two case reports of brain metastases in patients with pancreatobiliary neuroendocrine carcinoma

Brain metastases are extremely rare in patients with pancreatobiliary neuroendocrine caricnoma (PB-NEC). In this case report, we report two rare cases of brain metastases in patients with PB-NEC. Each patient was diagnosed with brain metastases five and ten months after the initial diagnosis of PB-NEC. It is noteworthy that the serum tumor marker neuron-specific enolase (NSE) or pro-gastrin-releasing peptide (Pro-GRP) was elevated, although the primary and metastatic lesions other than in the brain were under control with systemic chemotherapy. Moreover, the patients complained of no neurological symptoms until they were diagnosed with brain metastases. Although the incidence of brain metastases of PB-NEC is exceedingly low, it is important to keep in mind the possibility of brain metastases during the course of treatment for PB-NEC. In addition, we discuss a strategy of treatment and screening for brain metastases of PB-NEC in this case report.