Necrotizing sialometaplasia – 坏死性涎腺化生

Image taken from Clinical Guide to Oral Diseases.

Necrotizing sialometaplasia is a benign ulcerated lesion that is located at the back of hard palate. The lesion initially appears as a tender erythematous swelling that later changes into a deep, well-circumscribed ulcer covered with yellow-gray slough that is easily detached, leaving an ulcer with erythematous and granulomatous base. The ulcer is thought to be caused by an ischemic necrosis of the minor salivary glands due to local anaesthesia or burns and heals in 6 to 10 weeks, while the salivary ducts show a characteristic metaplasia.

• Pseudoepithelial hyperplasia is seen at the mar gins of the ulcer.
• Ischemic necrosis is characteristic and plays an important role in the pathogenesis of the ulcer.
• Squamous metaplasia of the ducts of minor salivary glands is characterized by the changes of the normally cuboidal ductal epithelium to stratified squamous, and is often accompanied by local inflammation or necrosis.