Necrotizing Sialometaplasia



Necrotizing sialometaplasia (NS) is a nonneoplastic inflammatory condition of the salivary glands. In 1973, Abrams et al first reported this condition.[1] The clinical and histopathologic features of necrotizing sialometaplasia often simulate those of malignancies such as squamous cell carcinoma or salivary gland malignancy.[2] All subsequent reports of necrotizing sialometaplasia stress the importance of correct diagnosis. Familiarity with necrotizing sialometaplasia and correct diagnosis are paramount in avoiding misdiagnosis and inappropriate treatment. Ischemia of salivary gland tissue leading to infarction (trauma) is the most likely cause.

A related Medscape Reference article that may be of interest is Cancers of the Oral Mucosa.


Necrotizing sialometaplasia was first reported to involve the minor salivary glands of the oral cavity, particularly those of the palate. Seventy-five percent of all cases occur on the posterior palate.[3] Most are unilateral, with one third occurring in a bilateral or midpalatal location. Reports of this entity in the minor glands of the retromolar pad area, buccal mucosa, tongue, incisive canal, and labial mucosa followed. In addition, necrotizing sialometaplasia is recognized in the parotid and submandibular salivary glands,[4] minor mucous glands in the lung,[5] nasal cavity,[6, 7] larynx,[8, 9] trachea,[10] nasopharynx, and maxillary sinus.[11] Similar lesions are identified in the breast; the condition is referred to as posttraumatic lobular metaplasia of the breast.[12]



United States

Mesa and colleagues reported an incidence of 0.03% based on findings in 10,000 oral biopsy specimens.[13] However, they state that this percentage does not account for cases of necrotizing sialometaplasia that heal spontaneously without biopsy.


Necrotizing sialometaplasia is reported worldwide. Isolated cases and reviews from Europe, North America, South America, and Asia are reported in the literature.


The lesions of necrotizing sialometaplasia often are painless; less frequently, they cause pain and numbness. The clinical appearance that suggests cancer is the significant feature of this lesion. The clinical pictures show a patient with a lesion thought to be cancer who underwent biopsy and was monitored for 9 weeks. Over that time, regression of the lesion can be seen (see the images below).

View Image

Initial presentation.

View Image

Three weeks later after biopsy.

View Image

At 6 weeks.

View Image

Nine weeks. Salivary gland infarction.


Brannon and colleagues[14] reported that cases of necrotizing sialometaplasia in whites outnumbered cases in blacks by a ratio of 4.9:1. Given the ratio of whites to blacks in the United States, a significant racial predilection does not appear to exist.


The male-to-female ratio is approximately 2:1.


The average age of patients with necrotizing sialometaplasia in the Armed Forces Institute of Pathology (AFIP) registry is 47.9 years, with a range of 17-80 years. The average age is 43.1 years for female patients and 50.3 years for male patients. A case of necrotizing sialometaplasia in an 18-month-old infant is reported.


Most cases of necrotizing sialometaplasia appear to arise spontaneously, whereas others are associated with a history of trauma, vomiting,[15, 16] radiation therapy, or surgery.[15] An association with neoplasia, such as parotid tumors, false vocal cord squamous cell carcinoma, and maxillary sinus carcinoma, is also reported. Cases associated with inflammatory conditions such as relapsing polychondritis and acute and chronic sinusitis have been noted to occur in the subglottic and sinus regions, respectively.


Necrotizing sialometaplasia manifests as a swelling with or without ulceration in anatomic sites that have mucous or serous glandular tissue.

The typical clinical presentation of necrotizing sialometaplasia is that of a crateriform ulcer of the palate that simulates a malignant process. These ulcerated lesions are 1-3 cm and are usually unilateral, but bilateral synchronous lesions and metachronous lesions can occur.[17, 18, 19]

Some lesions of necrotizing sialometaplasia may present as a submucosal swelling, without ulceration of the overlying mucosa. An intact surface mucosa may be noted in an evolving lesion at the time of diagnosis, although most cases are accompanied by mucosal ulceration. Erosion of the palatal bone may occur in either ulcerated or nonulcerated lesions.

Examination of a biopsy specimen is usually required to establish the correct diagnosis and to exclude a malignant or infectious process or an inflammatory condition such as Wegener granulomatosis. Extranodal lymphoma also may be considered in the clinical differential diagnosis of a palatal swelling or ulceration.


In most cases of necrotizing sialometaplasia, the etiology is believed to be related to vascular ischemia. Cases are reported in which vascular compression is caused by a necrotic myocutaneous reconstruction flap, embolization from carotid endarterectomy, sickle cell anemia,[20] Buerger disease,[21] or Raynaud phenomenon.[21]

The association of adjacent neoplasia that results in ischemic necrosis of the glandular elements and the histologic features of necrotizing sialometaplasia supports this pathogenic mechanism. In an experimental study in a rat model, local anesthetic injections induced necrotizing sialometaplasia.[22] Tobacco use is suggested as a possible etiologic risk factor for necrotizing sialometaplasia.

Imaging Studies

A definitive tissue diagnosis of necrotizing sialometaplasia should exclude the need for radiographic imaging. If erosion of the palatal bone occurs with or without perforation, radiologic examination may be performed.[23]


Incisional biopsy is necessary to establish the diagnosis of necrotizing sialometaplasia (NS). An inadequate biopsy specimen may lead to the misdiagnosis of squamous cell carcinoma or mucoepidermoid carcinoma. Findings in a superficial or limited biopsy specimen may be misinterpreted as a nonspecific ulcer or pseudoepitheliomatous hyperplasia of the surface mucosa.

Histologic Findings

The microscopic features of necrotizing sialometaplasia include coagulative necrosis of glandular acini and squamous metaplasia of its ducts. Mucin pooling is present, and an associated inflammatory infiltrate consists of macrophages; neutrophils; and, less commonly, lymphocytes, plasma cells, and eosinophils.

Pseudoepitheliomatous hyperplasia of the overlying mucosa can also be present, but the cytologic features of the squamous component are usually bland. Occasionally, isolated mucous cells may be entrapped within the squamous islands; these cells should not be confused with those of mucoepidermoid carcinoma.

The microscopic differential diagnosis for necrotizing sialometaplasia includes mucoepidermoid carcinoma and squamous cell carcinoma. Some believe that subacute necrotizing sialadenitis is yet another entity that occurs within the spectrum of necrotizing sialometaplasia; it should be distinguished from necrotizing sialometaplasia.

Medical Care

Necrotizing sialometaplasia (NS) resolves spontaneously. No treatment is necessary.

Surgical Care

Surgical care for necrotizing sialometaplasia consists of incisional biopsy for diagnostic purposes.

Further Outpatient Care

Periodic evaluation of the affected site is recommended until spontaneous resolution occurs.


The prognosis for necrotizing sialometaplasia (NS) is excellent. Spontaneous resolution usually occurs within weeks, although in the case presented, the lesion took more than 9 weeks to reach complete healing.

The average healing time for necrotizing sialometaplasia of the minor salivary glands of the hard and soft palates is approximately 5 weeks. The size of the lesion and whether or not bony perforation has occurred are clinical parameters that may influence the healing time.


John Svirsky, DDS, Director of Oral Pathology Diagnostic Service, Professor, Department of Oral and Maxillofacial Pathology, Virginia Commonwealth University School of Dentistry

Disclosure: Nothing to disclose.


John E Fantasia, DDS, Chief, Division of Oral Pathology, Department of Dermatology, Long Island Jewish Medical Center, North Shore-Long Island Jewish Health System

Disclosure: Nothing to disclose.

Josephine Wu, DDS, Assistant Director, Molecular Pathology Laboratory, Department of Pathology, Mount Sinai School of Medicine; Consulting Staff, Division of Oral and Maxillofacial Pathology, Department of Dental Medicine, Long Island Jewish Medical Center

Disclosure: Nothing to disclose.

Specialty Editors

Abdul-Ghani Kibbi, MD, Professor and Chair, Department of Dermatology, American University of Beirut Medical Center, Lebanon

Disclosure: Nothing to disclose.

David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

Disclosure: Nothing to disclose.

Drore Eisen, MD, DDS, Consulting Staff, Department of Dermatology, Dermatology Research Associates of Cincinnati

Disclosure: Nothing to disclose.

Glen H Crawford, MD, Assistant Clinical Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Chief, Division of Dermatology, The Pennsylvania Hospital

Disclosure: Abvie Honoraria Speaking and teaching

Chief Editor

William D James, MD, Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine

Disclosure: Nothing to disclose.


  1. Abrams AM, Melrose RJ, Howell FV. Necrotizing sialometaplasia. A disease simulating malignancy. Cancer. Jul 1973;32(1):130-5. [View Abstract]
  2. Franchi A, Gallo O, Santucci M. Pathologic quiz case 1. Necrotizing sialometaplasia obscuring recurrent well-differentiated squamous cell carcinoma of the maxillary sinus. Arch Otolaryngol Head Neck Surg. May 1995;121(5):584, 586. [View Abstract]
  3. Schmidt-Westhausen A, Philipsen HP, Reichart PA. [Necrotizing sialometaplasia of the palate. Literature report of 3 new cases]. Dtsch Z Mund Kiefer Gesichtschir. Jan-Feb 1991;15(1):30-4. [View Abstract]
  4. Batsakis JG, Manning JT. Necrotizing sialometaplasia of major salivary glands. J Laryngol Otol. Sep 1987;101(9):962-6. [View Abstract]
  5. Zschoch H. [Mucus gland infarct with squamous epithelial metaplasia in the lung. A rare site of so-called necrotizing sialometaplasia]. Pathologe. Feb 1992;13(1):45-8. [View Abstract]
  6. Abrams AM. Necrotizing sialometaplasia of the nasal cavity. Otolaryngol Head Neck Surg. Mar 1986;94(3):416. [View Abstract]
  7. Chen KT. Necrotizing sialometaplasia of the nasal cavity. Am J Otolaryngol. Nov-Dec 1982;3(6):444-6. [View Abstract]
  8. Walker GK, Fechner RE, Johns ME, Teja K. Necrotizing sialometaplasia of the larynx secondary to atheromatous embolization. Am J Clin Pathol. Feb 1982;77(2):221-3. [View Abstract]
  9. Wenig BM. Necrotizing sialometaplasia of the larynx. A report of two cases and a review of the literature. Am J Clin Pathol. May 1995;103(5):609-13. [View Abstract]
  10. Romagosa V, Bella MR, Truchero C, Moya J. Necrotizing sialometaplasia (adenometaplasia) of the trachea. Histopathology. Sep 1992;21(3):280-2. [View Abstract]
  11. Bell GW, Loukota RA. Necrotizing sialometaplasia coincident with ipsilateral infarcted antral polyps. Br J Oral Maxillofac Surg. Feb 1996;34(1):129-31. [View Abstract]
  12. Hurt MA, Díaz-Arias AA, Rosenholtz MJ, Havey AD, Stephenson HE Jr. Posttraumatic lobular squamous metaplasia of breast. An unusual pseudocarcinomatous metaplasia resembling squamous (necrotizing) sialometaplasia of the salivary gland. Mod Pathol. Sep 1988;1(5):385-90. [View Abstract]
  13. Mesa ML, Gertler RS, Schneider LC. Necrotizing sialometaplasia: frequency of histologic misdiagnosis. Oral Surg Oral Med Oral Pathol. Jan 1984;57(1):71-3. [View Abstract]
  14. Brannon RB, Fowler CB, Hartman KS. Necrotizing sialometaplasia. A clinicopathologic study of sixty-nine cases and review of the literature. Oral Surg Oral Med Oral Pathol. Sep 1991;72(3):317-25. [View Abstract]
  15. Aframian D, Milhem I I, Kirsch G, Markitziu A. Necrotizing Sialometaplasia after Silastic Ring Vertical Gastroplasty: Case Report and Review of Literature. Obes Surg. May 1995;5(2):179-182. [View Abstract]
  16. Schöning H, Emshoff R, Kreczy A. Necrotizing sialometaplasia in two patients with bulimia and chronic vomiting. Int J Oral Maxillofac Surg. Dec 1998;27(6):463-5. [View Abstract]
  17. Rossie KM, Allen CM, Burns RA. Necrotizing sialometaplasia: a case with metachronous lesions. J Oral Maxillofac Surg. Dec 1986;44(12):1006-8. [View Abstract]
  18. Stafford RF, Sonis ST, Shklar G. Bilateral necrotizing sialometaplasia: a case report. J Oral Med. Apr-Jun 1981;36(2):28-30. [View Abstract]
  19. Niedzielska I, Janic T, Markowski J. Bilateral localization of necrotizing sialometaplasia: a case report. Cases J. Sep 8 2009;2:9068. [View Abstract]
  20. Mandel L, Kaynar A, DeChiara S. Necrotizing sialometaplasia in a patient with sickle-cell anemia. J Oral Maxillofac Surg. Jul 1991;49(7):757-9. [View Abstract]
  21. Rye LA, Calhoun NR, Redman RS. Necrotizing sialometaplasia in a patient with Buerger's disease and Raynaud's phenomenon. Oral Surg Oral Med Oral Pathol. Mar 1980;49(3):233-6. [View Abstract]
  22. Shigematsu H, Shigematsu Y, Noguchi Y, Fujita K. Experimental study on necrotizing sialometaplasia of the palate in rats. Role of local anesthetic injections. Int J Oral Maxillofac Surg. Jun 1996;25(3):239-41. [View Abstract]
  23. Aframian DJ. Necrotizing sialometaplasia-a practical approach to the diagnosis. Arch Pathol Lab Med. Jan 2010;134(1):17. [View Abstract]
  24. Ben-Izhak O, Ben-Arieh Y. Necrotizing squamous metaplasia in herpetic tracheitis following prolonged intubation: a lesion similar to necrotizing sialometaplasia. Histopathology. Mar 1993;22(3):265-9. [View Abstract]
  25. Granich MS, Pilch BZ. Necrotizing sialometaplasia in the setting of acute and chronic sinusitis. Laryngoscope. Sep 1981;91(9 Pt 1):1532-5. [View Abstract]
  26. Granick MS, Solomon MP, Benedetto AV, Hannegan MW, Sohn M. Necrotizing sialometaplasia masquerading as residual cancer of the lip. Ann Plast Surg. Aug 1988;21(2):152-4. [View Abstract]
  27. Jensen JL. Idiopathic diseases. In: Ellis GL, Auclair PL, Gnepp DR, eds. Surgical Pathology of the Salivary Glands. Philadelphia, Pa: WB Saunders; 1991:60-82.
  28. King DT, Barr RJ. Syringometaplasia: mucinous and squamous variants. J Cutan Pathol. Aug 1979;6(4):284-91. [View Abstract]
  29. Krishna S, Bk R. Necrotizing sialometaplasia of palate: a case report. Imaging Sci Dent. Mar 2011;41(1):35-8. [View Abstract]
  30. Nilsen R, Bernhoft CH, Gilhuus-Moe O. Necrotizing sialometaplasia. Int J Oral Surg. Dec 1978;7(6):580-4. [View Abstract]
  31. Oliveira Alves MG, Kitakawa D, Carvalho YR, et al. Necrotizing sialometaplasia as a cause of a non-ulcerated nodule in the hard palate: a case report. J Med Case Reports. 2011;5:406. [View Abstract]
  32. Pulse CL, Lebovics RS, Zegarelli DJ. Necrotizing sialometaplasia: report of a case after lower lip mucocele excision. J Oral Maxillofac Surg. Dec 2000;58(12):1419-21. [View Abstract]
  33. Russell JD, Glover GW, Friedmann I. Necrotizing sialometaplasia. J Laryngol Otol. Jun 1992;106(6):569-71. [View Abstract]
  34. Sneige N, Batsakis JG. Necrotizing sialometaplasia. Ann Otol Rhinol Laryngol. Mar 1992;101(3):282-4. [View Abstract]
  35. Taxy JB. Necrotizing squamous/mucinous metaplasia in oncocytic salivary gland tumors. A potential diagnostic problem. Am J Clin Pathol. Jan 1992;97(1):40-5. [View Abstract]

Initial presentation.

Three weeks later after biopsy.

At 6 weeks.

Nine weeks. Salivary gland infarction.

Initial presentation.

Three weeks later after biopsy.

At 6 weeks.

Nine weeks. Salivary gland infarction.