Schwannomas, or neurinomas, are generally benign, slow-growing, asymptomatic neoplasms originating from the Schwann cells of a nerve sheath. As a part of spindle cell mesenchymal tumours, schwannomas arising from the gastrointestinal tract (GIT) are unusual; however, when they occur, the most common site involved is the stomach, which represents 0.2% of all gastric tumours. We report the case of a 35-year-old female patient with a history of pulmonary tuberculosis presenting with a large palpable abdominal mass reaching up to the peritoneal cavity. The initial clinical impression was a tuberculous abdominal mass, a cyst, or a teratoma. However, intra-operative findings during a subtotal gastrectomy revealed an exophytic gastric serosal mass, which suggested a gastrointestinal stromal tumour (GIST). Post-operative histopathological findings showed a fascicular arrangement of neoplastic spindle cells with pallisading nuclei that showed intense positivity for S-100 protein, and were negative for CD117 and desmin in immunohistochemistry studies. These results confirmed the final diagnosis of a gastric schwannoma.