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Year : 2015  |  Volume : 26  |  Issue : 5  |  Page : 550-555
Surgical management of necrotizing sialometaplasia of palate

Balaji Dental and Craniofacial Hospital, Chennai, Tamil Nadu, India

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Date of Web Publication17-Dec-2015


Necrotizing sialometaplasia (NSM) is a rare benign, inflammatory disease of both major and minor salivary glands, although more commonly reported in the minor glands of the palate. The characteristic clinical presentation can perplex the clinician and may be mistaken for a malignant neoplasm, such as mucoepidermoid carcinoma, as well as invasive squamous cell carcinoma. The clinical and histological similarity between this entity and a malignant lesion may result in unnecessary or mis-treatment. Though clinically mimics malignancy, NSM is considered to be a self-limiting disease, and takes about 3-12 weeks to resolve. Majority of the case resolves itself or by supportive and symptomatic treatment. Surgical intervention is rarely required in NSM except the diagnostic biopsy. Herein we report the clinical, histopathological feature and surgical management of a case of NSM of hard palate in a young adult male.

Keywords: Necrotizing sialometaplasia, salivary glands, ulcerative lesion

How to cite this article:
Balaji S M, Balaji P. Surgical management of necrotizing sialometaplasia of palate. Indian J Dent Res 2015;26:550-5

How to cite this URL:
Balaji S M, Balaji P. Surgical management of necrotizing sialometaplasia of palate. Indian J Dent Res [serial online] 2015 [cited 2023 Mar 30];26:550-5. Available from:
An otherwise healthy 28-year-old male patient was referred with the complaint of the painful ulcerative lesion in the mucosa of the left side hard palate since 1 month [Figure 1]. The patient had no relevant history except the incident of recent extraction. He had earlier undergone extraction of an impacted left third molar elsewhere a month back, during which he reportedly received palatal injection twice. The patient noticed a small ulcerated area near the socket, along the site of injection region which gradually increased in size over the next 10 days. Though there is no pain he experienced mild sensory change with numbness in the palatal area. He was prescribed different antibiotics and analgesics by other practitioners, but it did not benefit his condition. There was no other related history or related findings. He was apyrexial, and there was no malaise. He further gave no relevant medical and family history.
Figure 1: Proliferating ulcer denuding the underlying bone in the left side of the hard palate

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On intraoral examination of the lesion, there was denuded necrotic area on the left side of the hard palate. The infiltrating ulcer was approximately of 3 cm × 4 cm with inflamed irregular raised borders covered over by the yellow-white necrotic slough. The ulcer was tender on palpation with few areas of erythema over the margins.

The patient had appreciable oral hygiene with no abnormality detected in the adjacent intraoral areas and pharynx. Submandibular and submental lymph nodes were tender on palpation. General examinations of all other systems were stable with no remarkable findings.

Fasting and postprandial blood sugars were within the normal limit. Urine analysis was negative for glucose and ketone bodies. Blood chemistry report was normal except for the increased white cell count (13.8 × 103). Negative results obtained for purified protein derivative test, venereal disease research laboratory and enzyme-linked immunsorbant assay. Paranasal sinus view showed clear sinuses with normal density. Chest X-ray was unremarkable.

The histopathological examination revealed a reactive necrotizing inflammatory process involving the minor salivary glands, with pseudoepitheliomatous hyperplasia of the overlying epithelium, but without evidence of dysplasia. In the fibrous connective tissue, squamous metaplasia of the salivary ducts, and acinar necrosis with preservation of the lobular architecture of the neighboring minor salivary glands was found. Chronic inflammatory cells surrounding the glandular tissue were also observed.

The ulcerated area was irrigated with copious amount of normal saline daily for about 1 week which resulted in the reduction of the erythematous swelling of the lesion with minimized bleeding and reduction in the size of the ulcer. At the end of 1 week, the bleeding stopped completely with the exposure of the palatal bone [Figure 2]. Surgical closure of the denuded area using palatal transposition flap was planned.
Figure 2: Denuded bone with surrounding areas of healed margins

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Differential diagnosis

Clinically, NSM, which presents as a deep necrotic ulcer can be confused with granulomatous diseases such as syphilitic gumma and deep mycosis infections, which may show a sharp demarcation. However, the syphilitic ulcer is usually seen in the tertiary stage of syphilis that may present as a clean surfaced ulcer with perforation of the palate, a feature untypical of NSM. The presence of opportunistic infections in patients with poorly controlled diabetes may mimic NSM. [1],[2]

Most commonly proposed and generally accepted etiology for NSM relates to ischemia. In cases of ischemia, there is salivary gland necrosis and ulceration of the overlying mucosa in seen typically. Hence, NSM is commonly seen in bulimia patients.

There is a wide spectrum of clinical presentations in NSM. Pain and rapid progression are almost universal features, with pain often described as sharp, and it often precedes mucosal changes. [3],[4] Occasionally, sensory changes, such as numbness or anesthesia of the mucosa, have been documented to occur early in the course of the disease, as was observed in the present case. [5],[6]

The differential diagnosis in such a situation includes malignancy of salivary gland tumors (adenoid cystic carcinoma, mucoepidermoid carcinoma, and polymorphous low-grade adenocarcinoma), although none of these entities have a rapidly progressing growth pattern. Other lesions which need to be ruled out, because they may present as rapidly progressing palatal ulcerations are Wegener disease, zygomycosis, and lymphoma, particularly angiocentric T-cell lymphoma. Other malignancies of maxillary sinus origin, palatal perforation from cocaine abuse, and tertiary syphilis should also be considered.

Computerized tomographic scan, cone-beam computerized tomography, or magnetic resonance imaging are superior to conventional radiography in evaluating the integrity of palatine bone, which should not be compromised in NSM but might be affected in some of the malignancies considered in the differential diagnosis, as well as in Wegener disease, zygomycosis, or tertiary syphilis.

A biopsy of suspected NSM should be generous and deep to avoid sampling only necrotic material, and it should be performed with the use of a scalpel and not electrocautery or laser, to avoid confusing genuine necrosis with thermal coagulation. Paralleling the wide spectrum of clinical presentation in NSM, there is also a wide variability in the microscopic findings, depending on the stage of the lesions at the time of biopsy. Anneroth and Hansen defined the pathogenesis of NSM by five histologic stages: Infarction, sequestration, ulceration, reparative stage, and healed stage. [7]

Surgical procedure

Under general anesthesia (GA), nasotracheal intubation done. Infiltration was done to minimize bleeding near the operating site. The necrotized margins were removed and copious irrigation done; the epithelium-denuded bone was exposed. Markings for the posterior based palatal flap were done on the right side (unaffected side) of the palatal mucosa. The planned palatal flap was raised subperiosteally and extended posteriorly on either side of the greater palatal arteries preserving its supply and transposed to close the defect and sutured to the underlying mucosa leaving the donor site to heal by epithelization [Figure 3] [Figure 4] [Figure 5] [Figure 6] [Figure 7] [Figure 8] [Figure 9]. The postoperative event was uneventful. Wound healing was satisfactory. Complete healing of the donor site achieved in the follow-up 3 months period. Satisfactory healing with no recurrence during the follow-up period of 1 year [Figure 10] [Figure 11].
Figure 3: Preoperative image

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Figure 4: The erythematous margins are removed around the ulcer

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Figure 5: Marking of the palatal flap

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Figure 6: The palatal flaps are raised subperiosteally

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Figure 7: Subperiosteal dissection of the palatal flaps is extended posteriorly on either side of the greater palatine arteries

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Figure 8: Rotation of the pedicled palatal flap

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Figure 9: Suturing of the palatal flap

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Figure 10: Postoperative satisfactory healing achieved in 1 month

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Figure 11: Postoperative satisfactory healing achieved in 3 month

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   Discussion Top

NSM is a benign, self-healing lesion of salivary glands, which represents <1% of biopsied oral lesions. [8] It may arise in any area containing salivary gland tissue but more commonly over the hard palate. Other sites where it has been reported include a nasal cavity, trachea, parotid gland, sublingual gland, submandibular gland, larynx, buccal mucosa, maxillary sinus, tongue, tonsils, and retromolar trigone. Up to 10% of cases have been reported in major salivary gland. [9]

NSM was first reported in 1973 by Abrams et al. as reactive necrotizing inflammatory process involving minor salivary gland of the hard palate. [10] In the WHO classification of salivary gland tumors, NSM is classified under the group of tumor-like lesions. [11] These lesions are relatively rare and benign. Hence, it should not be confused with malignant lesions both histopathologically and clinically, particularly squamous cell carcinoma and mucoepidermoid carcinoma. [2],[12]

NSM is a rare disease with poorly understood etiology and pathogenesis. The specific etiology of NSM remains unknown; an infectious, probably viral, etiology has been implied, because the first reports occurred in groups of closely inhabiting military personnel, but several ultrastructural studies failed to identify viral particles. [13],[14]

Mechanical trauma has also been suggested as a predisposing factor for NSM because in some cases it developed after extractions of maxillary teeth. [3],[5],[15] In these cases, injecting a local anesthetic to the hard palate may contribute to ischemia through two possible mechanisms: Pharmacologic vasoconstriction and tissue resistance. Whereas lidocaine alone has a vasodilatatory effect, adrenaline or noradrenaline are often combined with lidocaine for their vasoconstrictive properties to reduce bleeding and prolong the anesthetic effect, and they, therefore, may cause tissue ischemia. [16],[17] In addition, the specific mechanical properties of the hard palate, with its tight tissues, may have a contributory role. Tissue resistance to local infiltration may result in increased pressure on the submucosal vessels during injection. This hypothesis has been partially supported by animal studies, inducing NSM in rats by palatal injections of lidocaine and epinephrine. [18] Hence, this could be attributed as the cause of NSM in the present report who had a recent history of dental treatment.

Several cases of NSM have occurred following GA, which may also represent a form of local trauma, either as an accidental traumatic event during intubation or extubation or due to prolonged local pressure. The agents used to induce GA generally have a peripheral vasodilating effect; however, their specific effect on the palate has not been investigated. [19],[20] Other possible predisposing factors cited in the literature are chemical irritation resulting from bulimia, gastroesophageal reflux disease, or following silastic ring vertical gastroplasty. Bulimic patients will often use their fingers to mechanically induce vomiting. So again, there may be a combination of mechanical and chemical factors affecting these patients. [4],[21] The low pH of the gastric contents contacting the oral mucosa is suggested as a major etiologic factor. [5] As there are only sporadic cases reported in the literature, there is no enough evidence published to correlate the frequency or the methods used to induce vomiting with NSM.

Smoking, as well as the use of some drugs, may decrease blood flow to the mucosa, and hence they are considered to be predisposing factors for NSM. Other compounds, such as cocaine, may be applied to the nasal or oral mucosa and are recognized as factors inducing ischemia and necrosis of nasal mucosa and cartilage as well as palatal perforation.

The present case contributed evidence to support the infarct theory. The sequestration and ulceration processes were observed in the case. The lobular pattern, which is usually described as being recognizable, was also preserved in the case. Extension of pools of mucin into the adjacent tissues elicits an inflammatory reaction, dominated by histiocytes and granulation tissue. The inflammatory component within the necrotic lobules is often minimal, but it is usually peripherally prominent. [22] However, in cases of secondary infection by bacteria and yeast forms a dense inflammatory infiltrate can also be seen in these areas.

In very rare cases, NSM has been described to occur alongside a true salivary gland malignancy, such as adenoid cystic carcinoma and angiocentric T-cell lymphoma, so a generous biopsy and meticulous examination should always be employed, to ensure that NSM is the only existing pathology. [23],[24],[25] Rarely, NSM has been reported to occur following a biopsy or surgical treatment of other salivary gland pathologies, such as mucocele. [26] After the biopsy, most cases are self-limiting and usually require only supportive treatment, including pain control and local antiseptics. The case presented has a significantly more aggressive course, resulting in a huge necrotic lesion involving half of the palate within about 2 weeks from onset. An attempt to control the disease by saline irrigation and curettage result in marked improvement except the presence of epithelium-denuded bone.

In different conditions outside the oral cavity, masses of necrotic tissue (following ischemic events, hypothermia, fungal infection, or any other cause) tend to get secondarily infected and may result in septicemia, especially when the area of necrosis is extensive. Therefore, wound debridement is known to be a vital adjunct in the care of patients with severe necrotic lesions. [27],[28] Healing of necrotic tissue is slow and accompanied by pain. Therefore, shortening the healing time by removing large masses of necrotic tissue should be considered as a viable treatment option. In our patient, given the mass necrosis and the vast colonization by both bacteria and yeast forms surgical debridement followed by covering of the denuded bone was considered to be a necessity, and healing was achieved with no systemic complications.

Although there is usually no need for surgery in the treatment of NSM, it can be a valuable tool in selected cases with unusually large diameters. [27],[28] In conclusion, the findings of the present case and literature review provide evidence that NSM may present with a wide variety of clinical and microscopic features, as well as multiple suspected but largely unproven contributory factors. Hence, clinicopathologic correlations are important for a definitive diagnosis. The hypothesis of ischemia as an etiologic factor has been supported by the microscopic findings in the present study. Although in the majority of cases NSM is self-limiting and heals spontaneously with only minimal supportive treatment, rare cases may reach significantly large sizes. In these cases, surgical debridement followed by flap coverage should be considered as a viable treatment option, providing better conditions for healing as well as decreasing the risk of sepsis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

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Correspondence Address:
S M Balaji
Balaji Dental and Craniofacial Hospital, Chennai, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.172086

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]

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