AbstractClear cell carcinoma is an extremely rare form ofmalignant salivary gland tumour. A case of clear cellcarcinoma arising in the minor salivary glands isr e p o r t e d .

Key words: Clear cell carcinoma, salivary glands, casereport.

(Received for publication October 1994. RevisedFebruary 1995. Accepted February 1995.)

IntroductionClear cell carcinoma of salivary gland origin is a

lesion that is recognized as an entity in some classi-fications, but not in others.1

Clear cells may be seen as a component of anumber of different benign and malignant salivarygland tumours. Thus, many authors believe thatclear cell carcinoma is a vague and imprecise entity.2

When clear cells are a minor component of asalivary gland tumour, appropriate classification canusually be determined by the predominanth i s t o p at h o l o gic feat u r e s. There are cases ofmucoepidermoid carcinomas and acinic cell adeno-carcinomas, where clear cells may be a distinctfeature. It is tempting to extrapolate these findingsto predominantly clear cell tumours and classifythem as mucoepidermoid carcinomas or acinic celladenocarcinomas.3-5

Case repor tA 54 year old male was admitted to the university

clinic, complaining of a six-month history of atumour on the right side of the palate.

Australian Dental Journal 1997;42:(1):8-10

Clear cell carcinoma of the minor salivary glands.Report of a case

E. Triantafillidou, MD, DDS*I. Dimitrakopoulos, MD, DDS*A. Skordalaki, MD†

The tumour was painless, mobile and was notadherent to the overlying normal mucosa (Fig. 1).Lymph nodes were not palpable in the neck.R a d i o graphic and laborat o ry examinations we r enormal.

A tentative diagnosis of a tumour of the minors a l i va ry glands was made, and under generalanaesthesia the tumour was removed by pericapsularexcision.

The microscopic examination of the tumourrevealed cytological features of malignancy with amild mitotic frequency, and unclear pleomorphism.The bulk of the tumour consisted of undifferentiatedi n t e rm e d i ate cells or poorly differentiated epi-dermoid cells, in which it was difficult to see theintercellular bridges. Hydrotropic degeneration in

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*Assistant Professor, Department of Oral and Maxillofacial Surgery,A ristotle Unive rsity of Thessaloniki, Greece.†Head, Department of Pat h o l o g y, G. Papanikolaou Hospital,Thessaloniki, Greece. Fig. 1. – Preoperative photograph of the tumour.

The origin of the clear cells is controversial. It isbelieved that these tumours originate in the inter-calated duct cells or that the myoepithelial cells arethe progenitor of the clear cells.11

Hydrotropic degeneration in the squamous cellsof mucoepidermoid carcinoma can produce areasof clear cells and occasionally these are the pre-dominant feature (clear cell variant). Sebaceouscarcinomas may include clear cells but these containlipid droplets giving the cytoplasm a ‘foamy appear-ance’. Clear cells may also be present in va ri a b l en u m b e rs in acinic cell carcinomas. They have theshape and morphology of acinar or intercalated duct-like cells that have lost their cytoplasmic staining.2 , 4 , 5

The most important differential diagnosis in thecase of an intra-oral clear cell carcinoma is a metas-tasis particularly from the kidney. Clear cell tumoursalso occur at other sites, such as the lung, thyroidand female genital tract, but no reports of such atumour first presenting as an intra-oral metastasishave been found.4

The occurrence of clear cell carcinoma in apleomorphic adenoma is not unexpected becauseboth tumours are probably derived from intercalatedducts.12-14

Although most tumours with a major clear cellcomponent are classified as low-grade malignancyt u m o u rs, close follow-up is advisable. In theliterature there are few cases of recurrence, as in this

Australian Dental Journal 1997;42:1. 9

the epidermoid cells produced areas of clear cellsand these were the predominant feature (Fig. 2).

Ten months later the patient was admitted again tothe clinic because of a recurrence of the tumour inthe same region. CT examination demonstrated asoft tissue mass without evidence of erosion of theunderlying maxillary bone. CT examination of theneck revealed no evidence of metastatic disease.Chest X-ray examination and ultrasound of thekidneys were normal. Under general anaesthesia thetumour was completely excised with a margin ofclinically healthy tissues. The defect in the palate wa sclosed with transpositional flaps. The microscopice x a m i n ation of the tumour was similar to the firs t .

The patient’s progress has been monitored forthree years after the second operation and there hasbeen no evidence of recurrence of the tumour.

DiscussionClear cell carcinoma is found primarily in the

major salivary glands, especially in the parotid. Itmay, however, be found in the minor salivary glandsand in other intraoral sites. These tumours accountfor less than 1 per cent of primary tumours of alltypes of salivary glands.6,7 Approximately 60 cases ofclear cell carcinoma, so-called glycogen-ri c hadenoma or clear cell myoepithelial adenoma orclear cell carcinoma of intercalated duct origin, oradenomyoepithelioma, have been reported.8-10

Fig. 2. – Infiltrative pattern of growth of clear cell carcinoma intonormal salivary gland parenchyma. H&E, x 100.

Fig. 3. – Hydrotropic degenerated squamous cells produced areas ofclear cells (arrows). H&E, x 400.

case, and fewer cases of metastatic disseminationhave been reported. 1,4,5,11,15

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08. Corio RL, Sciudda JJ, Brannon RB, Batsakis JG. Epithelial-myoepithelial carcinoma of intercalated duct origin; a clinico-pathologic and ultrastructural assessment of sixteen cases. OralSurg Oral Med Oral Pathol 1982;53:280-7.

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10. L attanzi DA, Po l ve rini P, Chin DC. Glycogen rich adenocarci-noma of a minor saliva ry gland. J Oral Maxillofac Surg1 9 8 5 ; 4 3 : 1 2 2 - 4 .

11. Shafer WG, Hine MK, Levy BM. A textbook of oral pathology.4th edn. WB Saunders, 1983:251.

12. Littman CD, Alguacil-Garcia A. Clear cell carcinoma arising inpleomorphic adenoma of the salivary gland. Am J Clin Pathol1987;88:239-43.

13. Klijanienko J, Micheau C, Schwaab G, et al. Clear cell carci-noma arising in pleomorphic adenoma of the minor salivarygland. J Laryngol Otol 1989;103:789-91.

14. Batsakis JG. Malignant mixed tumor. Ann Otol Rhinol Laryngol1989;91:342-3.

15. B atsakis JG, Regezi JA. Selected controve rsial lesions of saliva rytissue. Otolaryngol Clin North Am 1977;10:309-28.

Address for correspondence/reprints:Dr E. Triantafillidou,

Department of Oral and Maxillofacial Surgery,School of Dentistry,

Aristotle University of Thessaloniki,540 06 Thessaloniki,

Greece.

10 Australian Dental Journal 1997;42:1.