Necrotising sialometaplasia is a benign inflammatory condition of the salivary gland remnants or elements, which is usually self-limiting. It is most commonly found on the palate.
Most patients are more than 40 years of age, with a male: female ratio of 2:1. It is rarely seen in children. The palate is the most common site involved, usually located in the back of the hard palate.
Starts as non-ulcerated swelling with pain. In 2-3 weeks, the necrotic tissue leads to ulcer(s). The condition is usually self-limiting and shows complete remission subsequently without treatment within 6 to 10 weeks.
Uncertain, possibly secondary to ischaemia of the salivary tissue leading to infarction. Other postulated causes include:
- abnormal dentures causing chronic irritation to the palate
- following adenoidectomy in children
- prior surgery
- local trauma
- dental injections
- alcohol abuse
- cocaine use
- upper respiratory infections
- adjacent tumour growths
Acinar necrosis is found in early lesions. Subsequently, concomitant squamous metaplasia is seen. Despite necrosis, the lobular architecture of the glands is preserved. Metaplasia may mimic a malignant lesion, hence recognition of this condition is paramount.
Five histological stages have been described: infarction, sequestration, ulceration, reparation and healing.
Despite squamous metaplasia, malignant transformation is very rare.
Soft tissue density swelling of the palate which may show ulceration
They are seen as lobulated submucosal palatal lesions
- T1: hypointense
- T2: hyperintense
- T1 C+: thin peripheral enhancement
Possible differential considerations include
- mucoepidermoid carcinoma
- squamous cell carcinoma
- granulomatous diseases (syphilitic gumma)
- fungal infections
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