| Necrotizing sialometaplasia | |
|---|---|
 | |
| Specialty | ENT surgery |
Necrotizing sialometaplasia (NS) is abenign,ulcerativelesion, usually located towards the back of thehard palate. It is thought to be caused byischemicnecrosis (death oftissue due to lack of blood supply) ofminor salivary glands in response totrauma. Often painless, the condition is self-limiting and should heal in 6–10 weeks.
Although entirely benign and requiring no treatment, due to its similar appearance tooral cancer, it is sometimesmisdiagnosed asmalignant. Therefore, it is considered an important condition, despite its rarity.
The condition most commonly is located at the junction of the hard andsoft palate.[1] However, the condition may arise anywhere minor salivary glands are located.[nb 1] It has also been occasionally reported to involve the major salivary glands.[2][3] It may be present only on one side, or both sides.[1] The lesion typically is 1–4 cm in diameter.[4]
Initially, the lesion is a tender,erythematous (red) swelling. Later, in the ulcerated stage, the overlying mucosa breaks down to leave a deep, well-circumscribed ulcer which is yellow-gray in color and has a lobular base.[1]
There is usually only minor pain,[1] and the condition is often entirely painless. There may beprodromal symptoms similar toflu before the appearance of the lesion.[4]
The exact cause of the condition is unknown.[4][5] There is most evidence to supportvascular infarction and ischemic necrosis of salivary gland lobules as a mechanism for the condition.[6] Experimentally,local anaesthetic injections and tying of thearteries is reported to trigger the development of tissue changes similar to NS in lab rats.[6] Factors which are thought to cause this ischemia are listed below, however sometimes there is no evident predisposing factor or initiating event.[6]
Differentiation between this andSCC would be based on a history of recent trauma or dental treatment in the area.
Immunohistochemistry may aid the diagnosis. If the lesion is NS, there will be focal to absent immunoreactivity forp53, low immunoreactivity for MIB1 (Ki-67), and the presence of4A4/p63- andcalponin-positivemyoepithelial cells.[2]
No surgery is required.[4]
Healing is prolonged, and usually takes 6–10 weeks.[1] The ulcer heals bysecondary intention.[7]
The condition is rare.[8][9] The typical age range of those affected by the condition is about 23–66 years of age.[4] It usually occurs in smokers.[9] The male to female ratio has been reported as 1.95:1,[5] and 2.31:1.[10]
NS was first reported by Abramset al. in 1973.[11][6]