Clinical Case Discussion

Clinical history and photographs contributed by Drs. Antonio Caso and Ross Beirne, Department Oral & Maxillofacial Surgery, University of Washington.

Case History

This is a 62-year-old man who was referred to the Harborview Medical Center by a community clinic in Seattle. Patient reported cheese-burn of the roof of his mouth five weeks ago. As a result he developed an ulcer (Fig1) which didn't go away. He reported it to be mildly uncomfortable but said that it “looked worse than it felt." The ulcer had not changed in size over the duration of five weeks. His past medical history is significant for alcoholism, smoking (35 pack/year history), and hypertension. Patient is on Atenalol, HCTZ and Ranitidine.

Based on the history and clinical presentation the differential diagnosis should include squamous cell carcinoma despite the fact that palate is an uncommon location. It should also include necrotizing sialometaplasia and an infectious process such as deep fungal infection. The biopsy showed inflammatory reaction with large areas of acinar necrosis supporting the diagnosis of necrotizing sialometaplasia. Patient was placed on Peridex rinse and followed up every 2 weeks. Over the next 4 to 6 weeks, the lesion resolved with no further surgical intervention.

Discussion

Necrotizing sialometaplasia is a spontaneous, self-healing, and rapidly growing benign inflammatory lesion primarily affecting the minor salivary gland tissue. It usually heals within three months of occurrence (1). However, it is clinically an aggressive-looking lesion as is the case with this patient (Fig 1), making it hard for the dentist not to refer the patient for a biopsy especially with history of alcoholism and heavy smoking. It is of unknown etiology, but transient local ischemia is suggested as a possible etiology (2), such as a vasoconstrictor effect from dental injections. This hypothesis is supported by the histology of infracted salivary gland acini with intact cell membrane histology seen in coagulative necrosis. The ischemic necrosis hypothesis was supported in an animal study when restricting the blood supply to the salivary glands produced a histology of acinar cell necrosis similar to that seen in humans with this condition (2).

This lesion is more common in the fourth and fifth decade of life, and occurs more often in males (2:1 male:female ratio), but has been described in teenagers (1-3). The palate and the junction of hard and soft palate are the most common locations, accounting for the locations of about 75% of cases (2-3). Other locations, such as the buccal mucosa, lip, pharynx, and the major salivary gland tissue including the parotid and submandibular glands, are affected only rarely. It presents as single, bilateral or multiple ulcers. The ulcers are deep and necrotic with a flat edge. They can reach more than three centimeters in diameter. The clinical symptoms range from asymptomatic to mild pain or parasthesia. The clinical presentation can be mistaken for a malignant neoplasm of surface epithelium or salivary gland neoplasm (4).

The surface ulceration coupled with pseudoepitheliomatous hyperplasia can be mistaken for well differentiated squamous cell carcinoma invading the underling connective and salivary gland tissue. This misdiagnosis can also be made based on the changes seen in the salivary gland ducts; the Salivary gland duct epithelial metaplasia and hyperplasia can be mistaken for a low-grade adenocarcinoma of salivary gland origin (4). The histology combined with the aggressive clinical presentation can deceive both the surgeon and the pathologist. However, acinar necrosis with retention of lobular architecture should be of assistance in rendering a benign histologic diagnosis.

No treatment is recommended, but a biopsy is recommended to establish the baseline diagnosis. Most lesions heal within ten weeks after biopsy. If, for an unknown reason, the area does not heal, we recommend a second biopsy. It is very important that dentists are aware of this condition to help minimize over diagnosis and unnecessary over treatment.

References

1. Keogh PV, O’Regan E et al. Necrotizing sialometaplasia: an unusual bilateral presentation associated with antecedent anaesthesia and lack of response to intralesional steroids. Case report and review of the literature. Br Dent J. 2004; 196: 79-81
2. Abrams AM, Melrose RJ et al. Necrotizing sialometaplasia: A disease simulating malignancy. Cancer 1973; 32: 130-135.
3. Brannon RB, Fowler CB et al. Necrotizing sialometaplasia: A clinicopathologic study of 69 cases and review of the literature. Oral Surg Oral Med Oral Pathol 1991; 72: 317-325.
4. Sandmeier D, Bouzourene H. Necrotizing sialometaplasia: a potential diagnostic pitfall. Histopathology. 2002; 40: 200-201.

For questions or comments, please email Dolphine Oda at doda@washington.edu