Gastric schwannoma: a case report

Gastric schwannomas are rare, benign mesenchymal tumours that closely mimic gastrointestinal stromal tumours (GISTs) on imaging, despite fundamentally different biological behaviour. We report a 74-year-old man with a background of proctocolectomy for rectal cancer, found incidentally to have a 5 cm exophytic gastric mass on surveillance gastroscopy. Endoscopic ultrasound-guided fine needle aspiration favoured schwannoma, and the patient underwent an uncomplicated laparoscopic gastric wedge resection. Histopathology confirmed gastric schwannoma with clear margins and no nodal involvement; immunohistochemistry was positive for S100 calcium-binding protein (S100)/SRY-box transcription factor 10 (SOX10) and negative for discovered on GIST-1 (DOG1)/CD117 (c-KIT)/smooth muscle actin (SMA)/desmin, excluding GIST. He recovered well and was discharged after 2 days, with a conservative surveillance endoscopy plan (6 months, then annually for 5 years) agreed at multidisciplinary team meeting. This case underscores the essential role of immunohistochemistry in distinguishing gastric schwannoma from GIST, and highlights the absence of a consensus surveillance protocol following resection.