BACKGROUND: Gastric teratoma is a rare neoplasm, particularly in neonates, and usually presents as a palpable abdominal mass. However, severe occult gastrointestinal bleeding is uncommon and often misdiagnosed. Imaging studies are crucial for the preoperative diagnosis of neonatal teratoma, but definitive diagnosis relies on pathological examination.
CASE PRESENTATION: A 28-day-old boy presented with abdominal distension accompanied by vomiting for 2 days without hematemesis or melena. A complete blood count upon admission showed a hemoglobin level of 37 g/L. Ultrasound and computed tomography scans indicated a large cystic, solid mass in the abdominal cavity (approximately 9.8 �� 8.8 �� 11.2 cm), containing nodules, septa, calcification, and fat, and causing gastrointestinal compression. The mass was misdiagnosed as lymphangioma with hemorrhage before surgery. During surgery, the upper pole of the tumor was found to be fused with the gastric wall of the greater curvature of the fundus of the stomach, with most of the tumor growing exophytically and a small portion growing into the gastric lumen. The tumor, along with part of the gastric wall at the attachment site, was completely removed. Postoperative pathological examination revealed an immature teratoma grade 1. After discharge, the patient's growth and development were normal, with no adverse manifestations.
CONCLUSIONS: Neonatal gastric teratoma with severe occult gastrointestinal bleeding is extremely rare and hence must be on the list of differential diagnoses of neonatal abdominal mass when a cystic solid mass is found, especially when accompanied by severe anemia without obvious gastrointestinal bleeding. Attention should be paid to the location of the lesion, which is predominantly in the left upper abdomen and has been significantly pushed and displaced by the gastrointestinal tract, and to the imaging characteristics of teratoma such as fat and calcification, which help to exclude other palpable masses encountered during the neonatal period.
