Oliveira Alves et al. Journal of Medical Case Reports 2011, 5:406 http://www.jmedicalcasereports.com/content/5/1/406 Page 2 of 3 Figure 1 Clinical features. A: Submucosal nodule on the right side of the hard palate in the absence of mucosal alterations (continuous arrow). B: Occlusal radiograph showing no abnormalities. C: Ulceration in the biopsy area after 14 days (continuous arrow). D: Healed area after 30 days. Seven days after surgery, the biopsy wound showed normal healing. Ulceration was noted in the biopsy area after 14 days (Figure 1C). The lesion had healed sponta- neously after 30 days, with the observation of clinical signs of involution of the nodule (Figure 1D). Discussion The exact etiology of necrotizing sialometaplasia is unknown, but ischemia of local blood supply in the sali- vary gland lobules is the most widely accepted theory. Causes of this ischemia include local trauma, local anesthesia, ill-fitting dentures, smoking, alcohol Figure 2 Histopathological features (H&E staining). A: Preservation of the lobular architecture (25×) (continuous arrow). B: Atrophic broken acini with leakage of mucus and ductal dilatation (100×) (continuous arrow). C: Ducts showing squamous metaplasia (continuous arrow) and a moderate stromal mononuclear inflammatory infiltrate (dotted arrow) (200×). D: The same aspects as shown in B and C at 400× magnification. consumption, radiation, allergies, upper respiratory tract infection, intubation, surgical procedures involving the area [2,3,5,8], cocaine use [1], and chronic vomiting [5,9]. In the present case, the cause of the lesion could not be established since our patient did not report any of these conditions. Necrotizing sialometaplasia can be found at any site that contains salivary glands [6], but mainly affects the minor salivary glands located in the hard palate [2,4,5,8]. The disease manifests as a deep-seated ulcer, measuring on average 1.8 cm in its major diameter [2]. Other less frequently involved sites include the maxillary sinus, ret- romolar pad, lower lip, tongue, oral mucosa, mucobuc- cal fold, tonsillar fossa, nasal cavity, incisive canal, larynx, and trachea. Involvement of the major salivary glands has been reported mainly after surgical interven- tions [2,3]. Bilateral involvement is rare [3]. Swelling is initially observed, followed by ulceration that may be accompanied by fever. Pain is a common symptom. Par- esthesia in the affected area is rare [2-4]. Necrotizing sialometaplasia mainly affects white men, with a male-to-female ratio of two to one. The average age at diagnosis is 46 years [2,3], although the case of a two-year-old girl diagnosed with the disease has been reported in the literature [8]. In the present case, the disease was diagnosed in a woman whose age was below the range reported for the disease. Our patient was a dentist and had a history of palatal swelling that had appeared three weeks earlier and presented with stab- bing pain in the absence of clinical alterations of the mucosa. These findings are important for the clinician, who must be aware that a swelling in the palate may not be an inflammatory process related to infection. The typical manifestation of necrotizing sialometapla- sia is a deep ulcer and the differential diagnosis includes granulomatous diseases such as syphilitic gumma and deep mycosis lesions, which may show a sharp demarca- tion. Opportunistic infections are common in patients with poorly controlled diabetes and may mimic necro- tizing sialometaplasia [8]. In the present case, no ulcera- tion was seen and the differential diagnosis was malignant salivary gland tumor, most likely mucoepider- moid carcinoma [2]. The microscopic findings of necrotizing sialometapla- sia include coagulation necrosis of glandular acini, an inflammatory response, pseudoepitheliomatous hyper- plasia of overlying epithelium, and maintenance of the lobular architecture [2-5,7,8]. Ductal squamous metapla- sia and reactive fibrosis can be seen in older lesions [2-4,6]. Anneroth and Hansen [9] used histopathology to classify necrotizing sialometaplasia into five stages: infarction, sequestration, ulceration, reparative stage, and healed stage. During infarction, necrosis of the glandular acini predominates and culminates in the