Biopsy is prohibited for oesophageal smooth muscle tumours, mainly to prevent any impact on subsequent surgical treatment. When an oesophageal smooth muscle tumour is examined by oesophagoscopy, it appears mainly as a round or oval mass protruding into the lumen, the surface mucosa is usually intact, the mass can move under the mucosa and may be missed when the tumour is small.
Therefore, mucosal biopsy should not be performed during oesophagoscopy to avoid injury and adhesion of the mucosa to the tumour, which may hinder subsequent surgical removal.