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Necrotising Sialometaplasia
What is Necrotising Sialadenometaplasia /
Sialometaplasia?

Necrotising Sialadenometaplasia / Sialometaplasia is
an uncommon, usually self-limiting, variably ulcerated,
benign (i.e. non-cancerous), inflammatory process,
predominantly affecting salivary tissue (any site in the
body that contains elements of the salivary gland,
from the
para-nasal sinuses to the lung).

The importance of the lesion is that it
mimics the
appearance of malignant disease
, both clinically and
microscopically.  Failure to recognize
necrotising
sialometaplasia
may result in unnecessary radical
surgery because of an erroneous pre-operative
diagnosis of
squamous cell carcinoma or
muco-epidermoid carcinoma.
Photos of Necrotising Sialometaplasia in the Palate
(
Roof of Mouth)
What is the Cause of Necrotising Sialadenometaplasia / Sialometaplasia?

Although the ætio-pathogenesis of necrotising sialometaplasia remains unknown
there is general consensus that a reduced blood flow (
ischæmic) event in the
salivary gland precedes the development of the lesion.

This condition may occur after local trauma, including surgical manipulation or
injection of local anæsthesia into the involved area.

For patients who have had surgery, the lesion becomes clinically evident in about 3
weeks or longer.  
Necrotising sialometaplasia may also appear spontaneously,
often without the history of prior surgical or traumatic event.  No particular oral
condition or habit has been associated with this condition to date.

The disease has been reported in patients with vasculopathies which predispose to
ischæmia (such as Sickle Cell Disease, where infarction may be a feature in
crisis,
Buerger’s disease and Raynaud’s phenomenon).

Addition of a
vaso-constrictor (such as adrenaline) to local anæsthetic solutions,
local radiotherapy, cocaine use, pressure from local
space-occupying lesions and
surgery have also been implicated.  The lesion may be more florid in pregnancy.

There is also an association with preceding
upper respiratory tract infection within
the previous few weeks, particularly acute on chronic
sinusitis and allergy.  It is
possible that the
ischæmic event in these cases is due to immune complex
disease
, similar to the ætiology of erythema multiforme or benign trigeminal
sensory neuropathy
.

It has been suggested that
necrotising sialometaplasia of the palate may
represent an
ulcerative or necrotising stage of smoker’s keratosis although this
now seems unlikely.

Other predisposing factors include:

  • intubation
  • bronchoscopy
  • local anæsthetic injection
  • vascular damage due to trauma
  • smoking and alcohol
  • hot food
  • fellatio and
  • recurrent vomiting

There may be an association with tumours, specifically:

  • Warthin’s tumour
  • Abrisokov’s tumour
  • carcinoma of the lip
  • rapidly growing mesenchymal malignancy and
  • salivary gland tumours.


What are the signs and symptoms of Sialadenometaplasia / Sialometaplasia?

Men are affected approximately twice as often as women.  Mean age of
occurrence in men is about 50 years and 36 years in women (the youngest
reported case is 15 years).  There appears to be an increased incidence in males.  
There was a 5:1 preponderance of Caucasians over Afro-Caribbeans.

Necrotising sialometaplasia is extremely rare - there are barely 200 cases
reported in the world literature.

The vast majority (80%) of cases affect the
minor salivary glands of the palate,
while other sites include gum behind the lower wisdom teeth (
retro-molar pad), lip,
tongue and cheek.

The condition has also been reported in
major salivary glands.  Rarely, the
condition has also been reported at extra-salivary sites, which include:

  • nose
  • naso-pharynx
  • trachea
  • larynx and
  • lung.

At extra-salivary sites, the lesion may be described as
adenometaplasia.  A similar
lesion occurs in the skin, termed
syringometaplasia and similar histo-pathological
appearances have been described in the breast following trauma.

The lesion has a sudden onset, and is clinically characterized by a
nodular swelling
that leads to a painful, crater-like ulcer, 1 – 5 cm in diameter, with an irregular,
ragged border.  
The lesion mimics a carcinoma and is usually located on the
posterior palate (most commonly at the junction of the hard and soft palates).

Symptoms are generally disproportionately slight, compared with the size of the
lesion.  Most patients indicate surprisingly mild complaints of tenderness or dull
pain.  Pain may also be a feature at the onset and may be intense and referral of
the pain to the ear, eye and pharynx are variable features which have been
reported.  However, development of the lesion may be painless and there are even
reports of anæsthesia of the
Greater Palatine Nerve as the presenting feature.  
This is thought to be caused by involvement of the
vasa nervorum in the vasculitic
ætiological process.

The lesions may occur bilaterally and metachronously.

When ulceration occurs, it usually remains superficial, but a single case of full-
thickness
necrosis of the palate has been reported.

Injection of anti-inflammatory
steroids into the lesions appears to offer no benefit
on recovery time of the lesion or associated anæsthesia.

Differential diagnosis of an ulcer presenting with these features could include:

  • direct traumatic ulceration
  • major aphthous ulceration
  • syphilis
  • tuberculosis
  • deep mycosis
  • agranulocytosis
  • neutropænia
  • nicorandil-induced oral ulceration
  • malignancy, in particular squamous cell carcinoma, low-grade muco-
    epidermoid carcinoma and oncocytic malignancies.


How is it treated?

The lesion usually heals spontaneously within 4 – 8 weeks.

The usual management of this condition is simple observation until the healing
phase is complete.

Necrotising sialometaplasia may occur de novo, after trauma or a surgical
procedure or in association with other lesions, either benign or malignant.  Because
of the latter, whenever the diagnosis of
necrotising sialometaplasia is made, close
follow up is indicated until healing is complete.  Recognition of the histological
picture and the varied clinical settings in which
necrotising sialometaplasia can be
found, is essential to avoid histo-pathological mis-interpretation and inappropriate
treatment for this benign reactive condition.

The prognosis is excellent, once the correct diagnosis is made.

There are no known preventative strategies.

If the lesions are large, incisional biopsy should be done to establish a definitive
diagnosis.

Healing takes place over several weeks by secondary intention.  Reassuring the
patient and lavaging the wound with irrigation or rinsing may be helpful.  Once the
lesion has healed, recurrence and functional impairment are not anticipated.


Useful Website:

European Association of Oral Medicine


Useful Articles:

J American Dental Association 1996. Necrotizing sialometaplasia: literature review
and case reports.

Ear, Nose & Throat Journal 2003.  Necrotizing Sialometaplasia.

Oral Oncology 2006. Case Report. Necrotizing sialometaplasia of the palate.

J Canadian Dental Association 2007.  Sialometaplasia of the Soft Palate in a 2-
Year-Old Girl.

Cases Journal 2009.  Case report.  Bilateral localization of necrotizing
sialometaplasia.  A case report.

JOMS 2013.  Necrotizing Sialometaplasia in a Patient with an Eating Disorder -
Palatal Ulcer Accompanied by Dental Erosion Due to Binge-Purging

BDJ 2015.  Letters to the Editor.  Case Report.  Palatal mucosal necrosis after
administration of a palatal infiltration

BDJ 2016.  Mouth Cancer.  Acute Necrotising Sialometaplasia
Last Updated 5th May 2016