A 72-year-old man presents to his GP with increasing dyspepsia and weight loss. He has not experienced any other GI symptoms and physical examination is unremarkable. A barium meal is performed with the administration of intravenous Buscopan. The oesophagus is normal in appearance but a 'bull&;s eye' lesion is noted in the gastric mucosa. Which one of the following is not a recognised cause of this appearance?

Magenstrasse refers to the normal longitudinal mucosal folds seen adjacent to the lesser curve of the stomach during a barium meal. The 'bull&;s eye' appearance seen during a barium meal is due to a central ulcer in an elevated area of submucosa. A GIST may well have this appearance and neurofibromatosis can cause single or multiple target lesions. Melanoma is the commonest cause of submucosal gastric metastases.