Hisropathology 1978,2 , 19-29

Carcinomas of intraoral salivary glands T.STENE* & HANNA STROMME KOPPANG Department of Pathology, Dental Faculty, University of Oslo, Norway Accepted for publication 8 October 1977 STENET. & KOPPANG H.S. (1978)Hisropathology

2,

19-29

Carcinomas of intraoral salivary glands Of 44 intraoral salivary gland tumours received by the Department of Pathology, Dental Faculty, University of Oslo over the last 20 years, 21 (approx. 48%) were classified as carcinomas. Of these, the adenocarcinomas constituted the largest group, but because some of them bore a certain likeness to adenoid cystic carcinomas and to mucoepidermoid tumours, we believe that transitions exist between these groups of neoplasms. The material is thought to reflect the daily practice of oral surgeons and general dental practitioners, and we think it important to emphasize that approximately every second tumour in this series was malignant. Keywords: salivary gland carcinoma, intraoral salivary glands

Introduction Tumours of the intraoral salivary glands represent approximately 23% of all salivary gland tumours (Spiro, Koss, Hadju & Strong 1973). Previously published reports are in general agreement as regards the age, sex and site distributions of these tumours, but they show a comparatively wide variation in the incidence of malignancy: the reported percentages of malignant tumours range between 13 and 81 (Bergman 1969, Bhaskar & Weinmann 1955, Chaudry, Vickers & Gorlin 1961, Crocker, Cavalaris & Finch 1970,Luna, Stimson & Bardwill 1968). Most reports declare the adenoid cystic carcinoma to be the most common malignant tumour of the minor glands, representing between 20 and 50% of all the tumours of this origin, whereas mucoepidermoid tumours and adenocarcinomas constitute somewhat smaller groups (Chaudry et al. 1961, Frable & Elzay 1970, Luna et al. 1968, Main, Orr, McGurk, McComb & Mock 1976, Richardson, Dickason, Gaisford & Hanna 1975, Spiro et al. 1973). This report presents a series of 4intraoral salivary gland tumours received by the biopsy service of the Dental Faculty, University of Oslo over the last 20 years.

* Address for correspondence: Torbjorn Stene, Department of Pathology, Dental Faculty, University of Oslo, P.O. Box 1052,Blindern, Oslo 3, Norway. 0309-0167/78/010o-0019$02.00 01978 Blackwell Scientific Publications.

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T.Stene and H.S.Koppang

The biopsy service receives its specimens from oral surgeons, general dental practitioners and from the Department of Oral Surgery and Oral Medicine of the Dental Faculty, and the data in this series are thought to reflect the normal practice of these groups of dental practitioners. The purpose of the study was to find out the frequencies of the different histological types of intraoral sialocarcinomas and their age, sex and anatomical distribution.

Materials and methods The material consisted of 47 surgically removed and histologically confirmed, intraoral salivary gland tumours seen between 1957 and 1976 at the Department of Pathology. All specimens were re-examined, and a final diagnosis for each tumour was made according to the World Health Organization Classification (Thackray & Sobin 1972). The re-examination included study of clinical data and all available sections. New slides were prepared when necessary and stained with H & E, mucicarmine and PAS. Three cases were excluded from the series, two because they were re-diagnosed as extra-salivary pathological entities and one because it originated in the submandibular gland.

Results The anatomical location and age and sex distributions of the 44 tumours are given in Tables I & 2. The clinical and pathological data on the 23 adenomas (17 pleomorphic adenomas and 6 monomorphic adenomas) are in full agreement with those given in other reports and will not be reviewed here (Bergman 1969, Bhaskar & Weinmann 1955, Chaudry et al. 1961, Crocker et al. 1970, Evans & Cruickshank 1970, Luna et al. 1968). Of the remaining 21 cases, ie. 48% of the tumours, four were Table I. Age and sex distribution of 44 intraoral salivary gland tumours

Pleomorphic adenoma Monomorphic adenomas : adenolymphoma others Mucoepidermoid tumour Adenoid cystic carcinoma Adenocarcinoma Carcinoma in pleomorphic adenoma Total

* Not stated. * * One not stated.

4

(48) I

44

I3

45

I 2-88

55**

I 6-66 40-80 14-71

I 15

(34) 29 (66) 49

I 2-88

Intraoral sialocarcinomas

2I

Table 3. Anatomical distribution of 4intraoral salivary gland tumours

Palate

Upper Max. alv. Mand. alv. Buccal lip proc. proc. mucosa Tongue

-

Pleomorphic adenoma* Monomorphic adenomas : adenolymphoma others Mucoepidermoid tumour Adenoid cystic carcinoma Adenocarcinoma Carcinoma in pleomorphic adenonia Total

9

4

I

I

I I

5 2

I

1

4 6

3 I

2

3

3

I 22

I0

4

I

* One not stated. classified as mucoepidermoid tumours, seven as adenoid cystic carcinomas, nine as adenocarcinomas and one as carcinoma in a pleomorphic adenoma. The mean age of the 21 patients with carcinoma was a little higher than that of the patients with benign tumours (50 and 47 years), and 13 (62%) of the patients were female. The palate was the most common site of origin (13 cases, ie. 62%), followed by the maxillary alveolar process, buccal mucosa and mandibular alveolar process. MUCOEPIDERMOID TUMOURS

Four cases were diagnosed as mucoepidermoid tumours using the criteria of Thackray & Sobin (1972).Two were from the palate, one from the upper lip and one from the mandibular alveolar process. The age and sex distributions are given in Table I . The palatal tumours were moderately well differentiated and consisted of cystic spaces surrounded by columnar, mucus-producing cells, and of nests and islands of epidermoid cells intermingled with large, clear cells without mucin (intermediate, cells) and mucus-producing cells. Some nuclear and cellular pleomorphism was evident, especially in the epidermoid cells. The tumours were partly encapsulated, but unmistakeably malignant in that they encroached upon and invaded surrounding glands and mucosal epithelium. The tumour from the upper lip consisted almost exclusively of mucus-producing cells lining cystic, alveolar and tubular structures. In addition solid areas of clear, intermediate cells and a few epidermoid cells could be seen. Cellular isomorphism prevailed, but the tumour was clearly invasive (Figure I). The fourth mucoepidermoid tumour originated in or near the mandibular alveolar process. It was a poorly differentiated tumour consisting of invasive masses of pleomorphic epidermoid and clear cells with individual cell keratinization, keratin pearls and foci of necrosis (Figure 2). Diligent search revealed small groups of cells containing PAS- and mucicarmine-positive material scattered among the epidermoid elements, but their number was so small that the classification of the lesion as a mucoepidermoid tumour and not as an epidermoid carcinoma is disputable.

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TStene and H.S.Koppang

Figure I. Well differentiated mucoepidermoid tumour invading surface epithelium in upper lip. PAS. x 66. Figure 2. Poorly differentiated mucoepidermoid tumour from mandibular alveolar ridge with predominantly epidermoid and intermediate cells. H & E. x 66.

Intraoral sialocarcinomas

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The mucoepidermoid tumours constituted 9% of the entire material and 19% of the carcinomas. ADENOID CYSTIC CARCINOMA

Seven tumours, that is 16% of the whole material and 33% of the carcinomas, were diagnosed as adenoid cystic carcinomas. Six of the patients were female, and the mean age was 55 years, range 40-80 years. Four tumours were located in the palate and three in the maxillary alveolar process. They showed the usual range of histological appearances encountered in these tumours ; cribriform, cystic, solid and trabecular patterns and obvious invasive growth. Two cases deserve special mention. One was a palatal tumour which at operation showed infiltrative properties and which had resorbed the palatal bone and the roots of the two premolars on the left side. It consisted of large islands of small, ovoid or round hyaline bodies partly surrounded by small cells with dark nuclei and larger epithelial cells with finely granular nuclei and clear or weakly eosinophilic cytoplasm (Figure 3). Some cells were arranged in discrete islands and tubular structures and gave the impression of being of glandular derivation (Figure 4). The hyaline bodies were weakly mucicarmine-positive, moderately Congo-red-positive and PASnegative. The staining properties suggested a possible amyloid deposit, but the presence of glandular epithelium, the infiltrative growth and the size and distribution of the hyaline material seemed to justify the diagnosis ‘adenoid cystic carcinoma with extreme hyalinization’. The other tumour, also from the palate, consisted of thin, interconnecting strands of myoepithelial-type cells arranged in a mucoid matrix to give a lace-like pattern (Figure 5). It was reminiscent of patterns seen in some pleomorphic adenomas, but the tumour was invasive and contained no other structures typical of pleomorphic adenomas. It was therefore thought to represent an uncommon subtype of adenoid cystic carcinoma previously described by Lucas (1976) as a tumour with pronounced mucoid change. ADENOCARCINOMAS

Nine of the salivary gland tumours (20%) were classified as adenocarcinomas which thus represents the largest group (43%) among the carcinomas in this series. Six of them originated in the palate, two in the buccal mucosa and one in the mandibular retromolar area. The mean age of the patients at operation was 50 years, range 14-7 I years, and five of the patients were female. Four of the adenocarcinomas were mucus-producing. They consisted of cystic cavities, often with papillary projections, lined by columnar and sometimes cuboidal or flattened epithelial cells and mucus-producing cells. In addition, small solid areas of moderately pleomorphic polygonal cells were seen. Two cases resembled mucoepidermoid tumours, but the presence of typical adenopapillary structures and a general lack of epidermoid cellsjustified their inclusion into the adenocarcinomagroup. The remaining five adenocarcinomas were of the solid trabecular type consisting of sheets, islands and trabeculae of remarkably isomorphic epithelial cells (Figure 6). The cells were very similar to the ductal-type cells seen in the monomorphic adenomas,

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TStene and H.S.Koppang

Figure 3. Extremely hyalinized adenoid cystic carcinoma from the palate. H & E. x 66. Figure 4. Higher magnification of the tumour in Figure 3; hyaline globuli partly surrounded by epithelial cells. H & E. x 168.

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Figure 5. Mucoid adenoid cystic carcinoma from the palate. H & E. x 66. Figure 6.Solid trabecular adenocarcinoma from the palate. Note the cellular isomorphism. H & E. x 66.

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TStene and H.S.Koppang

and their mitotic activity was low. The tumours lacked capsular structures and infiltrated the surrounding tissues, vessels and nerves. A comparative study of the adenocarcinomas and the monomorphic adenomas of this series made us believe that the former could be considered as well-differentiated malignant counterparts of the latter, and that they probably behave biologically as the adenoid cystic carcinomas (Stene & Koppang 1977). Two of the adenocarcinomas also shared certain features with the adenoid cystic carcinomas. They consisted of solid islands of cells well-demarcated from the stroma the arranged in a basaloid pattern. However, they lacked cribriform, cystic and hyaline structures and were classified with the adenocarcinomas. CARCINOMA IN PLEOMORPHIC ADENOMA

One tumour from the palate of a 50-year-old man was diagnosed as carcinoma in a pleomorphic adenoma. It contained extensive areas that fulfilled the histological criteria of a pleomorphic adenoma, but it lacked a connective tissue capsule and contained malignant epithelial elements infiltrating the surrounding structures. The tumour was very cellular and contained few mesenchymal components.

Discussion This series of 44 intraoral salivary gland tumours, as well as some of the previously published reports (Chaudry et al. 1961, Crocker et al. 1970, Bhaskar & Weinmann 1955, Frable & Elzay 1970), indicate that about half of these are malignant growths. Luna et al. (1968), however, found that 81% were malignant, whereas Bergman’s (1969) figure was 13%. Furthermore, the reported frequencies of the different types of sialocarcinomas vary. These discrepancies may be due to two factors; variations in the histological criteria applied to the different series of tumours, and the type of institution from which they are reported. THE H I S T O L O G I C A L C R I T E R I A

The histological features of the different salivary gland tumours are now well established (Evans & Cruickshank 1970, Thackray & Sobin 1972). The mucoepidermoid tumours constitute between 5 and 23% of the intraoral salivary gland tumours (Bergman 1969, Crocker et al. 1970, Frable & Elzay 1970, Main et al. 1976), and most authors agree that they all are potentially malignant although of different degree of differentiation. In contrast to this, some authors claim that many low-grade mucoepidermoid tumours appear to be so benign that they may be classified as mucusproducing adenomas (Bhaskar & Bernier 1962, Main et al. 1976, Melrose, Abrams & Howell 1973). Our material is far too small to be involved in this discussion, but it illustrates two points that we feel are important. Firstly, one of our cases was a well differentiated tumour that consisted of mucus-producing, goblet-type cells arranged in glandular patterns. Nevertheless, it was clearly invasive. This supports the reports of Eneroth & Zetterberg (1976) and of Blanck, Backstrom, Eneroth & Jacobson (1974) stating that the most significantprognostic criterion in salivary gland

Intraorai siaiocarcinomas

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tumours is their behaviour towards surrounding structures and not their histological detail. The level of differentiation seems in other words to be of less importance in these cases than their mode of growth. Secondly, the histological diversity seen in these tumours make us believe, as did Main et al. (1976), that a continuum exists between the mucoepidermoid tumour on the one hand and epidermoid carcinoma and adenocarcinoma on the other. Three of our cases illustrate this; one was a poorly differentiated carcinoma of predominantly epidermoid structure which contained a few mucus-producing cells and which therefore, according to Thackray & Sobin (r972), should be classified as a mucoepidermoid tumour. The other two were mucusproducing adenocarcinomas resembling mucoepidermoid tumours. However, they lacked typical epidermoid elements, contained adenopapillary structures and were thus diagnosed as adenocarcinomas. The classification of adenoid cystic carcinomas is usually less problematic. The tumours in our material were clearly invasive neoplasms with characteristic adenoid cystic and cribriform structures. However, two cases from the adenocarcinoma group resembled these in that they consisted of islands and nests of cells welldemarcated from the stromal tissue. Although they contained some tubular elements, such as are seen in the adenoid cystic carcinomas, they lacked cystic and cribiform patterns and were hence classified with the adenocarcinomas. We feel, therefore, that transitions also exist between adenoid cystic carcinomas and adenocarcinomas, and that the allocation into one group or another is to some extent subjective. The classification of the highly hyalinized lesion as an adenoid cystic carcinoma is disputable. We feel that although the hyaline material had some staining properties of amyloid, the presence of glandular epithelium and the invasive and destructive properties of the lesion justify its classification as a malignant tumour of glandular origin. As hyaline material, often in globular or round masses, is found in varying amounts in most adenoid cystic carcinomas, this seems to be the most appropriate diagnosis. To the best of our knowledge, no such tumour has previously been reported from the oral region. The other unusual adenoid cystic carcinoma consisted of strings of epithelial or myoepithelial cells arranged in a mucoid matrix. This structure is often found in pleomorphic adenomas, but careful search revealed no other structures typical of this tumour. In addition, it was unquestionably infiltrative, and as such, it resembled the mucoid adenoid cystic carcinoma described by Lucas (1976). A report on the structure of the solid, trabecular adenocarcinomas is given elsewhere (Stene & Koppang I 977). As mentioned previously, their histological structure resembled that seen in some monomorphic adenomas, and this, in addition to a low mitotic activity and cellular uniformity, make us believe that they are slow-growing, well-differentiated carcinomas with biological properties comparable to the adenoid cystic carcinomas. As the number of cases is small (five), and as two of the patients have been lost to follow-up, this will have to be confirmed after collection of more cases. The classification of the border-line cases, such as those in our material, is to a certain extent a subjective matter. In studying small groups of tumours, such as this material and several other reported series of intraoral salivary gland tumours,

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TStene and H.S.Koppang

this should be borne in mind, especially when evaluating the incidence of the different types of tumours. Our series has a high percentage of adenocarcinomas compared with some other reports (Frable & Elzay 1970, Luna et al. 1968, Richardson et al. 1975), but our figures are comparable to those given by Chaudry et a/. (1961) and Main et al. (1976). Considering the diversity in the histological structure of the tumours, an exact subclassification of the sialocarcinomas seems to us to be of less importance than a thorough histological evaluation of the turnours’ behaviour and mode of growth. THE T Y P E OF I N S T I T U T I O N

The type of institution from which a series is sampled probably accounts for most of the variation in the reported percentages of malignant tumours from the intraoral glands. Some series are from hospitals with a high number of referrals of malignant tumours of the head and neck (Spiro et al. 1973), whereas others come from general hospitals without a special interest in these problems and from dental school biopsy services which receive material from both general dental practitioners and oral surgeons (Bergman 1969, Crocker et al, 1970). The present series is collected from a dental school biopsy service, and the data are thought to be significant to anybody working in the region of the mouth, ie. oral surgeons, dentists and ear, nose and throat specialists. The fact that about 50% of the intraoral salivary gland tumours are malignant should be clearly remembered when the surgical approach is being planned. T H E C L I N I C A L DATA

The findingsin this study as regards the favoured sites of occurrence of the intraoral sialocarcinomas are similar to those given in other reports. The palate is the most common site of origin (approx. 62%), followed by the maxillary alveolar process, buccal mucosa, mandibular alveolar process and upper lip (Table 2). 62% of the patients were female and the average age at operation was 50 years. These data are in agreement with those in other reports (Bergman 1969, Chaudry et al. 1961, Crocker et af. 1970, Frable & Elzay 1970, Luna et al. 1968, Main et al. 1976, Spiro et al. 1973). Follow-up data has been obtained on some of our patients. Unfortunately, many cases, especially the older ones, have been lost to follow-up, and the number of cases in our material with full information on surgical approach, recurrences and their treatment, cause of death etc., is too small to give any useful information about the best treatment and the behaviour of the different types of sialocarcinoma. This is, however, well documented in the quoted literature. The solid, trabecular adenocarcinomas are of special interest to us, but an evaluation of their behaviour and prognosis will require assessment of a larger series of cases. AcknowIedgement The authors wish to express their appreciation to Dr Alan H. Cruickshank, Reader in

Intraoral sialocarcinomas

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Pathology at the University of Liverpool, England, for his helpful advice with some of the cases.

References BERGMAN R. (1969) Tumors of the minor salivary glands, a report of 46 cases. Cancer 23,538-543 BHASKAR S.N. & BERNIER J.L. (1962) Mucoepidermoid tumors of major and minor salivary glands. Cancer 15,801-817 S.N. & WEINMANN J.P. (1955) Tumors of the minor salivary glands. A study of twentyBHASKAR three cases. Oral Surgery, Oral Medicine and Oral Pathology 8, 1278-1297 BLANCKC., BACKSTRGM A., ENEROTH C.-M. & JACOBSON P.A. (1974) Poorly differentiated solid carcinoma of the parotid gland. Acta Radiologica 13, 17-3 1 CHAUDRY A.P., VICKERS R.A. & GORLINR.J. (1961)Intraoral minor salivary gland tumours, an analysis of 1,414 cases. Oral Surgery, Oral Medicine and Oral Pathology 14, I 194-1225 R. (1970) Intraoral minor salivary gland tumors. Oral CROCKER D.J., CAVALARIS C.J. & FINCH Surgery, Oral Medicine and Oral Pathology 29, 60-68 ENEROTH C.-M. & ZETTERBERG A. (1976) A cytochemical method of grading the malignancy of salivary gland tumours preoperatively. Acta Otolaryngologica 81, 489-4515 EVANSR.W. & CRUICKSHANK A.H. (1970) Epithelial tumours of salicary glands. W.B.Saunders, Philadelphia FRABLE W.J. & ELZAYR.P. (1970) Tumors of minor salivary glands, a report of 73 cases. Cancer 25, 932-941 LUCASR.B. (1976) Adenoid cystic carcinoma. In Pathology of Tumours of the Oral Tissues, 3rd edn., pp. 329-335. Churchill Livingstone, Edinburgh LUNAM.A., STIMSON P.J. & BARDWILL J.M. (1968) Minor salivary gland tumors of the oral cavity. Oral Surgery, Oral Medicine and Oral Pathology 25, 7 1-86 MAINJ.H.P., ORRJ.A., MCGURKF.M., MCCOMBR.J. & MOCKD. (1976) Salivary gland tumors; review of 643 cases. Journal of Oral Pathology 5, 88-102 MELROSE R.J., ABRAMS A.M. & HOWELL F.V. (1973) Mucoepidermoid tumors of intraoral minor salivary glands: A clinicopathologic study of 54 cases. Journal of Oral Pathology 2, 314-325 RICHARDSON G.S., DICKASON W.L., GAISFORD J.C. & HANNAD.C. (1975) Tumours of salivary glands. An analysis of 752 cases. Plastic and Reconstructive Surgery 55, 131-138 SPIRO R.H., Koss L.G., HADJUS.I. &STRONG E.W. (1973) Tumors of minor salivary gland origin, a clinicopathological study of 492 cases. Cancer 31, I 17-129 STENET. & KOPPANG H.S. (1977) Monomorphic adenomas of the upper lip. O r d Surgery, Oral Medicine and Oral Pathology. Submitted for publication THACKRAY A.C. & SOBINL.H. (1972) Histological typing of salivary gland tumors. World Health Organization, Geneva

Carcinomas of intraoral salivary glands.

Hisropathology 1978,2 , 19-29 Carcinomas of intraoral salivary glands T.STENE* & HANNA STROMME KOPPANG Department of Pathology, Dental Faculty, Unive...
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