CASE REPORT

Necrotising sialometaplasia in the floor of mouth

Maria Devine & Stephanie Sammut & Brendan Conn &

Victor Lopes

Received: 16 April 2013 /Accepted: 12 June 2013# Springer-Verlag Berlin Heidelberg 2013

AbstractIntroduction Necrotising sialometaplasia is a benign self-limiting inflammatory process which occurs in the salivarygland tissue. The condition is a diagnostic challenge mim-icking malignancy both clinically and histopathologically.Commonly, it presents in the hard palate.Case report Here, we report an unusual case in a 56-year-oldman which presented in the floor of the mouth.

Keywords Salivary gland disease . Differential diagnosis .

Necrotising sialometaplasia

Introduction

Necrotising sialometaplasia (NS) is a benign inflammatoryprocess which is reported to occur in both minor and majorsalivary glands [1]. It was first described by Abrams et al. in1973 [2] as a benign, self-limiting, necrotising process involv-ing the mucous salivary glands on the hard palate [2]. NS hasbeen reported in many other anatomic locations containingsalivary gland tissue including the trachea, nasopharynx, pa-rotid gland, submandibular gland, sublingual gland, buccalmucosa, tongue, tonsil and maxillary sinus [3]. The lesionusually presents as a rapidly progressing, painful swelling,which becomes ulcerated, often with raised, indurated edges,

which can clinically and histopathologically resemble malig-nancy [3, 4], particularly squamous cell and mucoepidermoidcarcinoma [5].

Literature search using Pubmed revealed only two previ-ous case reports of NS presenting in the floor of the mouth[6, 7]. In one of these cases, the patient had undergone ahemiglossectomy and myocutaneous flap reconstructionfor squamous cell carcinoma of the tongue. NS occurred1 month later [6].

Case report

A 56-year-old male was referred to the Combined De-partment of Oral and Maxillofacial Surgery and OralMedicine at the Edinburgh Dental Institute with a pain-ful lump in the right floor of mouth. Medically, he wasfit and well and on no medication. He was a smoker often cigarettes a day and consumed alcohol in excess ofthe UK government recommended weekly maximumamount (21 units for men). He presented with a tender,firm, non-ulcerated 1.5-cm soft tissue expansion on thelingual aspect of the right mandible. Extraoral examina-tion was unremarkable and there was no associatedcervical lymphadenopathy. The patient wore a loweracrylic partial denture; however, this was not in contactwith the lesion therefore a denture-related traumaticulcer was not considered in the differential diagnosis.The clinical differential diagnosis included malignancy:primary or metastatic. Fine needle aspiration cytologywas non-diagnostic. The patient underwent urgentincisional biopsy of the lesion under general anaesthesiawithin the following days and histopathology showedmildly chronically inflamed salivary gland tissue only.

The patient was reviewed 2 weeks later and presentedwith a 2-cm-diameter ulcer with rolled edges, indurationand necrotic centre in the right floor of mouth (see Fig. 1).The ulcer was painful and the patient was finding it difficult

M. Devine : S. Sammut :V. LopesCombined Department of Oral and Maxillofacial Surgery and OralMedicine, Edinburgh Dental Institute, Lauriston Building,Lauriston Place, Edinburgh EH3 9HA, Scotland, UK

M. Devine (*)Edinburgh Dental Institute, Lauriston Building, Lauriston Place,Edinburgh EH3 9HA, Scotland, UKe-mail: maria.k.devine@gmail.com

B. ConnPathology Department, Royal Infirmary of Edinburgh, 51 LittleFrance Crescent, Edinburgh, Scotland EH16 4SB, UK

Oral Maxillofac SurgDOI 10.1007/s10006-013-0420-7

to eat. Due to the highly suspicious clinical features, it wasconsidered likely that initial biopsy may not have beenrepresentative and repeat incisional biopsy was undertaken.Histopathology showed focally ulcerated, diffusely inflamedparakeratinised squamous mucosa with prominent submuco-sal minor salivary glands. The glands demonstrated inflam-matory changes including interstitial fibrosis, acinar atrophyand chronic inflammatory infiltrates. Complex buds of squa-mous epithelium showing hyperchromatic nuclei and occa-sional mitotic figures were closely associated with the in-flamed salivary tissue and showed a lobular distribution.Focally, the epithelial buds appeared to fuse with the over-lying squamous epithelium. A thrombosed vessel was iden-tified at the deep aspect and there was a generalised back-ground of inflamed fibrous and granulation tissue (see Figs. 2and 3). These features were suggestive of necrotisingsialometaplasia; however, it was stressed that the floor ofmouth is not a typical site and the possibility that the featuresmay represent extension from an adjacent dysplastic or ma-lignant process could not be excluded. Close clinicopatho-logical correlation was therefore recommended. A CT scanwas requested which showed thickening in the right floor ofmouth but no discrete mass. There was no lymph nodeenlargement and the chest was normal.

The patient was reviewed on a weekly basis for 6 weeks, bywhich time the lesion had completely resolved with only scartissue visible in the right floor of mouth. On review 6 monthslater, he remains well and with no sign of recurrence.

Discussion

Necrotising sialometaplasia is a rare, benign and self-limiting inflammatory process involving the salivarygland tissue. A feature almost unique to this conditionis that it is a notorious mimic of malignancy bothclinically and histologically and presents a considerablediagnostic challenge. It is two to three times morefrequent in men and can present at any age, althoughmost patients are older than 40 years [8]. Although theaetiology is not completely understood, it is believed tobe caused by an ischaemic event leading to infarctionof the salivary gland acini [5]. Potential predisposing

Fig. 1 Clinical photograph showing ulcer on the floor of the mouth/ventral tongue with necrotic centre and rolled edges

Fig. 2 H & E ×40 necrotizing sialometaplasia: note the complex budsof squamous epithelium within the corium situated immediately be-neath the mucosal surface and appearing to merge with the inflamed,atrophic minor salivary gland at the deep aspect

Fig. 3 H & E ×100 necrotizing sialometaplasia. The bottom right ofthis picture shows salivary gland acini demonstrating variable degreesof degeneration within preserved lobular architecture. The top leftshows an adjacent focus of squamous metaplasia

Fig. 4 Ki67 ×100 necrotizing sialometaplasia: note the nuclear expres-sion of proliferation marker Ki67 restricted to the basal cell populationof the buds of squamous epithelium. This is a useful adjunct to mor-phology in the differential diagnosis as diffuse expression of Ki67 in themajority of cells would be more in keeping with squamous cell carci-noma rather than necrotising sialometaplasia

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factors have been suggested such as trauma caused bylocal anaesthetic injection, dental appliances, vomiting,surgical procedures, intubation, radiotherapy andsmoking [3–5]. Recently, a number of cases have beenreported in association with bulimia [8].

Typically, NS occurs on the palate. Presentation inthe floor of the mouth is unusual. Interestingly, a similarlesion was described by Lima [9] as a cystic lesion inthe floor of the mouth of a 70-year-old woman. Thecase presented here initially presented as a painfulswelling, with ulceration developing following biopsy.Treatment is symptomatic and usually NS resolvesspontaneously within 2–3 months [8].

Five histological stages in the development of NS havebeen described by Anneroth and Hansen: infarction, seques-tration, ulceration, repair and healing [10]. These may not bepresent in all cases and may overlap. The histopathologicalfeatures of NS include lobular necrosis of the salivaryglands, pseudoepitheliomatous hyperplasia of the adjacentepithelium and squamous metaplasia of the salivary ductalepithelium together with inflammation secondary to extrav-asation of mucin. Preservation of normal lobular architectureand lobular necrosis/infarction distinguish the lesion from asquamous cell carcinoma [11]. Despite these criteria, thedifferential diagnosis between NS remains difficult in somecases. The application of proliferation markers andmyoepithelial markers by immunohistochemistry has beenused and proposed as an adjunct to diagnosis but theirpractical use remains uncertain [12, 13] (see Fig. 4). Thehistological picture needs to be correlated with the clinicalfeatures and any obvious aetiologic event as often, onlyresolution of the lesion confirms the diagnosis [8]. Cautionshould also be exercised as there have been reports of NS andadenoid cystic carcinoma existing simultaneously within thesame lesion [14].

Due to the rare occurrence of NS, evidence in the litera-ture largely consists of isolated case reports and small caseseries; therefore, conclusions on the precise aetiology andpathogenesis are limited. Due to clinical and histologicalsimilarities to malignant disease, NS could be misdiagnosedleading to unnecessary intervention and possibility of expo-sure to surgical procedures with significant morbidity. Thepatient in this case underwent a general anaesthetic, CT scanand two surgical procedures before a definitive diagnosiswas reached.

Conclusion

Necrotising sialometaplasia is a rare lesion; however,clinicians should be aware of the floor of mouth as apossible site when considering a differential diagnosis ofclinically suspicious lesions.

Conflict of interest The authors declare they have no conflict ofinterest.

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