A Rare Case of Brain Metastasis of Gastric Neuroendocrine Carcinoma

Gastric neuroendocrine carcinoma (small cell neuroendocrine carcinoma [small cell NEC]) is a rare type of gastric cancer that is rarely encountered in clinical practice. Although solitary brain metastasis from gastric cancer is exceptionally rare, we present a case of solitary brain metastasis of gastric NEC. The patient was a 71-year-old man who had undergone surgery and chemotherapy for gastric NEC two years prior. During follow-up, computed tomography (CT) scans of the neck, chest, abdomen, and pelvis, along with tumor marker evaluations, revealed no evidence of metastasis. However, he developed left homonymous hemianopsia, prompting a head CT and magnetic resonance imaging (MRI). Imaging revealed a subcortical hemorrhage in the right temporal lobe and tumors in two locations: the right temporal lobe and the upper surface of the cerebellum. Tumor resection and hematoma removal were performed for diagnostic and decompressive purposes. Histopathological examination confirmed the diagnosis of brain metastasis from gastric NEC. Brain metastases from gastric cancer are rare, and to the best of our knowledge, only one English-language case report of solitary brain metastasis from gastric NEC has been published. We report this case and provide a discussion based on the available literature.