Developmental foregut cysts, whether bronchogenic, esophageal, gastroenteric or pericardial, are frequently encountered in the mediastinum, and are also occasionally found in the upper abdomen, where they can mimic adrenal, pancreatic, renal or gastric masses. We present the computed tomographic (CT) and histologic findings of an intramuscular bronchogenic cyst of the gastric body, mimicking a retroperitoneal cystic mass. CT scanning demonstrated the presence of a relatively hyperattenuating cystic mass without enhancement. Histologic examination revealed a bronchogenic cyst secreting mucoid materials.