Gastric Metastasis from Small Cell Lung Cancer: An Unusual Site of Metastatic Spread: A Case Report.

Background Small Cell Lung Cancer (SCLC) is a lung neuroendocrine tumor with high invasiveness and early extensive metastasis. The most common metastatic sites of SCLC include the brain, bone, liver, and adrenal gland, but gastric metastasis is uncommon. We report a case of SCLC metastasizing to the stomach and discuss its imaging findings, in order to enhance clinical understanding and emphasize the key role of imaging in identifying such uncommon metastasis. Case Presentation The patient was a 70-year-old male with no smoking history and was hospitalized due to dizziness and fatigue. Cranial and chest Computed Tomography (CT) showed nodules in the upper lobe of the left lung and intracranial space-occupying lesions, and the diagnosis of SCLC was confirmed by lung biopsy. Positron emission tomography-computed tomography further confirmed the presence of multiple metastases. A few months later, the reexamination found that the lung lesions progressed and the symptoms of abdominal distension occurred. Abdominal CT revealed a soft tissue mass in the fundus of the stomach, and endoscopic ultrasound further confirmed that it was a hypoechoic mass of submucosal origin. After gastroscopy combined with laparoscopic resection, the postoperative pathological and immunohistochemical findings supported the diagnosis of gastric metastasis from SCLC. Conclusion This case highlights that although gastric metastasis from SCLC is unusual, we should be alert to the possibility of gastric imaging abnormalities during follow-up. Comprehensive imaging, endoscopy, and pathological examination are essential for the diagnosis.