Necrotizing 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.
On this page:
Epidemiology
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.
Clinical presentation
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.
Etiology
Uncertain, possibly secondary to ischemia 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
- smoking
- cocaine use
- upper respiratory infections
- radiation
- adjacent tumor growths
- bulimia
Pathology
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.
Radiographic features
CT
Soft tissue density swelling of the palate which may show ulceration
MRI
They are seen as lobulated submucosal palatal lesions
- T1: hypointense
- T2: hyperintense
- T1 C+: thin peripheral enhancement
Differential diagnosis
Possible differential considerations include
- mucoepidermoid carcinoma
- squamous cell carcinoma
- granulomatous diseases (syphilitic gumma)
- fungal infections