Dysplastic pleomorphic adenoma of the sublingual salivary gland

BrrrirhJou1nalo/Oroland~UuxiN~~facia/Sur~rry(lYY3)31.394 395

I

I

Dysplastic pleomorphic adenoma of the sublingual salivary gland J. Clark,

B.M.W.

Bailey, J. W. Eveson

Department of Oral and Maxillofacial Surgery, A&ford Hospital, Middlesex; Centre for the Study qf Oral Disease, University of Bristol Dental Hospital and School, Bristol

SUMMAR

Y. All tumours of the sublingual gland are rare and paradoxically

the large majority are malignant. adenoma in the sublingual gland is described. The tumour showed areas of dysplasia and the difficulties in distinguishing this from benign pleomorphic adenoma or carcinoma in pleomorphic adenoma are considered, and the literature is reviewed. A case of pleomorphic

INTRODUCTION Primary neoplasms of the sublingual gland comprise 0.5- 1% of all epithelial salivary gland tumours (Spiro et al., 1989). However, a disproportionately large number of these are malignant (Batsakis, 1991). Monomorphic adenoma, adenocarcinoma and undifferentiated carcinoma each accounted for 14% of turnours of the sublingual gland in one series (Eveson & Cawson, 1985) while adenoid cystic carcinoma and carcinoma in pleomorphic adenoma each formed 28%. Paradoxically, pleomorphic adenomas are rarely seen. In total, therefore, 80-90% of sublingual gland tumours are frankly malignant (Eneroth 1969; 1971). The present report describes a case of pleomorphic adenoma of the sublingual gland which showed in addition dysplastic changes.

Fig. 2 - Microscopy shows a cellular area of the plcomorphic adenoma with mild dysplasia and four mitotic ligures (arrowed). H & E x 300.

Case report a hard lesion measuring 5 x 2 cm in the right sublingual gland with no radiological evidence of a calculus. There was no associated lymphadenopathy. The right sublingual gland was excised in toto and the postoperative course was uneventful. Five years later the patient has no evidence of recurrence or metastasis. Initial histological classification was a pleomorphic adenoma of the sublingual salivary gland. There were areas of myxochondroid matrix and typical double-layered ductlike structures some containing eosinophilic secretions (Fig. I). In view of the paucity of literature relating to benign tumours of the sublingual gland the specimen was submitted to the British Salivary Gland Tumour Panel for further assessment. Re-examination of the tumour showed focal areas in which there was a high mitotic rate considered outside the normal limits of a purely benign pleomorphic adenoma (Fig. 2). The term ‘dysplastic pleomorphic adenoma’ was given to this tumour.

A 40-year old Caucasian female was referred by her general dental practitioner in 1986 with a painless mass in the floor of the mouth of unknown duration. Examination showed

DISCUSSION Fig. 1 - Microscopy shows an area of typical pleomorphic adenoma with myxochondroid matrix and double-layered like structures. H & E x 60.

Pleomorphic adenoma is the most common major salivary gland tumour. In a review of 2410 cases by Eveson & Cawson (1985), pleomorphic adenoma

duct394

Dysplastic

accounted for 63.3% of parotid gland tumours, 59.5% of submandibular gland tumours and 42.9% of minor salivary gland tumours. However, no pleomorphic adenomas were seen in the sublingual gland. problems associated with The main clinical pleomorphic adenoma are the risk of recurrence following surgery and the tendency of some tumours to show progression to malignancy (Seifert et al.: 1990). Malignancy is, however, uncommon. In the review by Eveson & Cawson, 1985, carcinoma in pleomorphic adenoma accounted for 3.2% of parotid gland tumours, 7.8% of submandibular gland tumours, 7.1% of minor salivary gland tumours and 28.6% of sublingual gland tumours. Carcinoma in pleomorphic adcnoma has been increasingly distinctly delimited in recent years but there is still considerable disagreement regarding its malignancy and certain histological features are considered to indicate potential malignancy or ‘dysplasia’ (Eneroth et al., 1968). The most clearly acceptable histological feature of malignancy in carcinoma in pleomorphic adenoma is destructive infiltrative growth (Eneroth et al., 1968; Gerughty et al., 1969; Bolts et al., 1973). Other features which should arouse suspicion of malignant change in pleomorphic adenoma are highly pleomorphic and hyperchromatic nuclei among the epithelial elements, increased numbers of mitotic figures, spontaneous infarct-like necrosis in the epithelial and stromal components of the neoplasm, and excessive hyalinisation and calcification of the stroma (Eneroth et al., 1968; Gcrughty et al., 1969; Batsakis, 1971). According to Eneroth et al., (1968) these tumours are the most malignant of all tumours afflicting the salivary glands with no long-term survivors. Rates of recurrence and metastasis arc high, the commonest sites being lymph nodes, lung and bone (Eneroth et al., 1968; Gerughty et al., 1969; Batsakis 1971; Anderson et al., 1991). A common clinical feature of pleomorphic adenomas which develop carcinomatous changes is long duration before they assume a malignant character. Indeed, it is now recognised that there may be an earlier period of ‘dysplasia’ showing cellular atypia and excess mitotic activity but no evidence of frank invasion (Seifert, 1991). Such tumours have been also called carcinoma - in-sifu, non-invasive carcinoma in pleomorphic adenoma and intracapsular carcinoma in pleomorphic adenoma (Seifert et al., 1990; Scifcrt, 1992). No logical objections can be raised to each of these descriptive terms and perhaps ‘dysplastic pleomorphic adcnoma’ would be the most appropriate designation. These cases appear not to have a tendency to recurrence or metastasis, presumably because (by definition) they are removed at an early stage in tumour progression. This assumption, however, remains to be verified by long-term follow-up studies. The conundrum therefore remains. Carcinoma in pleomorphic adcnomas accounts for 28% of sublingual tumours (Eveson & Cawson, 1985) but pleo-

pleomorphic

adenoma

of the sublingual

salivary

gland

395

morphic adenomas of the gland remain virtually unreported. Can one readily progress to the other? The presence of dysplasia in the present case would tend to support the hypothesis. References Andersen, L. J.. Therkilsden, M. H., Ockelmann, H. H., Bentren, J. D.. Schiodt, T. & Hansen II. S. (1991). Malignant epithelial tumors in the minor salivary glands, the submandibular gland and the sublingual gland. Prognostic factors and treatment results. Cancer, 68,243 I. Batsakis, J. G. (1971). Benign and malignant mixed tumors of the salivary glands. (/nieersitJ: ofMichigan Mediral C’et71er Journal. 37, 178. Batsakis, J. G. (1991). Sublingual gland. Annals of Otology. -. Rhinology and Luryngoigy, iOO,521. Boles. R.. Johns. M. E. & Batsakis. J. G. (1973). Carcinoma in plcomorphic adenomas of salivary ghtnds.‘Anncl/s of Orology. 82,684. Encroth, C. M. (1969). Incidence and prognosis of salivary-gland tumours at different histologic sites. Acra Ofo-Lmyngologica, 263, 174. Eneroth. C. M. (1971). Salivary gland tumors in the parotid gland, submandibular gland and the palate region. Cancer, 27, 1415. Eneroth. C. M., Blanck. C. & Jakobsson. P. A. (1968). Carcinoma in pleomorphic adenoma of the parotid gland. Acra OfoI.urpgologicu, 66,477. Eveson, J. W. & Cawson, R. A. (1985). Salivary gland tumors. A review of 2410 casts with particular reference to histological types. site, age and sex distribution. Journal of’Purhology, 146, 51. Gerughty. R. M., Scofied, H. H., Brown, F. M. & Henniger, G. R. (1969). Malignant mixed tumours of salivary gland origin. Cancer, 24,47 I Seifcrt. G. (1991). WHO International Classification ofTumours. Histological Typing of Salivary Gland Tumours. 2nd Edn. Berlin & Heidelberg, Springer-Verlag. Scifcrt. G. (1992). Histopathology of malignant salivary gland tumours. Oral Oncology, 28B, 49. Seifcrt. G.. Brocheriou, C., Cardesa, A. & Eveson, J. W. (1990). WHO international histoloeical classification of tumours. Tentative histological classi‘iication of salivary gland tumours. Polhology Re.~u1~cl7 and Practice. 186, 555. _ Sniro, R. H.. Armstrong. J.. Harrison. L.. Geller. K. L.. Lin. P-Y. & Strong, E. W. (1989). Carcinoma of major salivary glands. Rcccnt trends. Archives of Otolaryngolog)j- Head and Neck Surgery. 115,3 16.

The Authors J. Clark BDS Senior House Officer B.M.W. Bailey MB, FRCS, FDSRCS Consultant Department of Oral and Maxillofacial Surgery Ashford Hospital London Road Ashford Middlesex TW I5 3AA J. W. Eveson PhD, FDS, FRCPath Reader/Consultant in Oral Medicine and Pathology Ccntrc for the Study of Oral Discasc University of Bristol Dental Hospital and School Lower Maudlin Street Bristol BSI 2LY Correspondence

and requests

Paper received 29 March Accepted 8 July 1993

1993

for offprints

to B.M.W.

Bailey