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Basal cell adenomas of the minor salivary glands
I I
I
[
II
I
Basal cell adenomas of the minor salivary glands A clinicopathologic study of seventeen new cases and a review of the UterabJre John E. Fantasia, D.D.S.,* and Brad W. Neville, D.D.S., ** Philadelphia, Pa., and Atlanta, Ga. TEMPLE
UNIVERSITY
SCHOOL
OF DENTISTRY
AND EMORY
UNIVERSITY
SCHOOL
OF DENTISTRY
The basal cell adenoma (BCA) is a benign monomorphic salivary gland tumor. Those of minor gland origin tend to occur within or adjacent to the upper lip (80 percent). The BCA is an encapsulated, slow-growing lesion which most commonly affects older persons. Several different histologic patterns can be noted, and often a combination of these variations is present within the same tumor. Simple surgical excision appears to be adequate treatment.
T h e salivary gland basal cell adenoma (BCA) is an unusual type of monomorphic adenoma which occurs in both the major and minor glands. These lesions appear to have certain distinct clinical and pathologic features. Historically, BCAs were once considered a variant of the benign mixed tumor. 1 More recently, Kleinsasser and Klein 2 and Evans and Cruickshank 3 have defined and separated this isomorphic epithelial tumor from the benign mixed tumor. The lack of both myoepithelial cells and myxochondroid elements distinguishes the BCA from mixed salivary gland tumors. 2 Electron microscopic studies by Hiibner and associates, 4 Min and colleagues, 5 and Luna and Mackay 6 have confirmed the absence of myoepithelial cells in this tumor. Basal cell adenomas of the major salivary glands occur most frequently in the parotid gland. 7 The present report deals with the clinical and pathologic features of BCAs of the minor salivary glands of the oral cavity. MATERIALS AND METHODS
Seventeen minor salivary gland BCAs from the files of the Departments of Oral Pathology of the Temple University and Emory University Schools of Dentistry
This study was supported in part by Grant No. CA19456-04 and Fellowship Grant No. 19253-04 from the National Cancer Institute, Bethesda. Md. *Assistant Professor, Departmentof Pathology, Temple University School of Dentistry. **Clinical OncologyFellow, Departmentof Oral Pathology, Emory University School of Dentistry. 0030-4220/80/110433+08500.80/0
(~) 1980 The C. V. Mosby Co.
were studied with the light microscope. The clinical data were also tabulated. A preliminary analysis comparing the clinical data of our seventeen cases with previous reports of BCAs of the minor glands revealed no significant differences. These cases were combined, yielding a total of seventy for analysis. REVIEW OF THE LITERATURE
Table I represents those cases obtained from a review of the literature, with the available clinical data. Eggers, s in 1928, reported on mixed tumors of the palate. However, in two of his cases (Nos. 6 and 7), he noted "the conspicuous absence of mucoid connective tissue and cartilage." He did not include these cases in his series of benign mixed tumors but simply referred to them as " a d e n o m a s . " The photomicrographs show acceptable BCAs, and therefore they are included in this review. In 1967 Kleinsasser and Klein 2 reported a series of BCAs, including one of minor salivary gland origin. Christ and Crocker, 11 in a review of BCAs of minor glands, included three cases of their own along with previously published cases by Bhaskar and Weinmann, 9 Evans and Cruickshank, 3 and Davis and Davis. 10 Klein and Goldman ~2 reported one case in 1973. In an addendum to their article, they mentioned the occurrence of another BCA in the buccal mucosa of a 74year-old woman. Both of these cases are included in Table I. Nelson and Jacoway 14 reported the largest series of BCAs, consisting of twenty-nine cases which they
434
Fantasia and Neville
Oral Surg. N o v e m b e r , 1980
Table I. Reported cases of basal cell adenoma Location No.
Adjacent upper
of Author
cases
Age
Sex
Race
Upper lip
Lip, not
lip
L o w e r lip
.
4 1
--
--
2
1
1
65
M
--
Evans and Cruickshank a
2
40
F
--
56
F
--
1
3
1
--
--
1
--
1
87
M
W
l
Christ and Crocker 1~
3
56
M
W
l
60
F
W
1
78
M
W
1
59
M
W
1
74
F
--
73
M
W
Mean,
16M
17W
23
60
13F
Nelson and Jacoway 14
1 28
-1
Kerr 15
1
41
M
--
--
Harrison TM
1
51
F
--
--
S t r y c h a l s k i iv
1
71
F
W
1
Crumpler et at. is Ahren and Lindstrom ~
2 60
M
--
l
64
M
--
l
2
.
.
Wiener 2°
1
67
F
B
1
F i l m and Giunta 21
l
71
F
W
l
17
Mean,
l IF
14W
14
3
61
6M 32F 31M
IB 39W 2B
50
6
Fantasia and Neville Total
70
Mean, 61
2
1
Davis and Davis l°
Bollinger and Hiatt 13
.
Palate
2
2
.
Buccal mucosa
Eggers s Bhaskar and W e i n m a n n a Kleinsasser and Klein 2
Klein and Goldman TM
.
specified
termed monomorphic adenoma, canalicular type. One case was from the parotid gland; therefore, it was deleted from their total number of cases. However, we did use their clinical data as they presented it, aware that the one parotid lesion is reflected in these data. In 1974 H a r r i s o n 16 performed histochemical studies on a BCA o f the buccal mucosa. Kerr ~5 reported the occurrence of a pleomorphic salivary adenoma in the lower lip. Examination of the photomicrograph suggests that this is a BCA, and it is included as such. Crumpler and associates ~8 reported eleven cases of
.
.
.
2
.
2
.
3
.
3
6
BCA, two of which arose from minor salivary gland tissue. Wiene:a° reported what appears to be the first case in a non-Caucasian. Additional case reports by Bollinger and Hiatt, la Strychalski, 17 Ahr6n and Lindstr6m, la and Frim and Giunta 21 are also listed.
CLINICAL FEATURES The patient's age was available in sixty-two of the seventy cases. The age range was from 33 to 87 years, with a mean age of 61 years. The location was stated in all seventy cases. Fifty
Volume 50 Number 5
Basal cell adenomas of minor salivary glands
435
Fig. 1. Low-power photomicrograph demonstrating a tubular and trabecular architecture. Note the fibrous connective tissue capsule. (Hematoxylin and eosin stain. Original magnification, ×40.) occurred in the upper lip, six were adjacent to the upper lip, two were found in the lower lip, and three were present within the lips but the specific location was not stated, three occurred in the buccal mucosa, and six were present on the palate. Fifty-six cases (80 percent) occurred within or adjacent to the upper lip. There was no sex predilection. The patient's sex was known in sixty-three cases, with thirty-two of the tumors occurring in women and thirty-one occurring in men. The patient's race was known in forty-one cases. Thirty-nine patients were white and two patients were black. Follow-up information was available in fourteen of our seventeen cases. The range was from 1 to 48 months, with a mean follow-up of 17.3 months. Recurrence has not been noted in any of these cases. Of the fifty-three cases reviewed from the literature, follow-up information was provided in thirty, with no recurrences reported. Follow-up ranged from 2 to 128 months with a mean follow-up of 32 months. Combining our cases with those from the literature, follow-up information is available on forty-four of seventy cases, with no recurrences noted. Follow-up ranges from 1 month to 128 months, with a mean of 27.3 months. Additional clinical data from our seventeen cases follow. Four of the seventeen were described as painful. Surgical excision was the mode of treatment in all
seventeen cases. The most common clinical diagnosis was mucocele, which was rendered in nine cases. Other diagnoses included in the clinicians' differentials were sebaceous cyst, nasolabial cyst, thrombosed oral varix, lipoma, and salivary gland tumor.
MICROSCOPIC FEATURES These neoplasms consisted of basaloid epithelial cells which were most commonly arranged in a tubular and/or tmbecular pattern (Figs. 1 and 2). Solid nests or sheets of cells were occasionally noted (Figs. 3 and 4). The tumors frequently exhibited a combination of the different patterns, with one of the patterns (tubular, trabecular, or solid) usually predominating. Large cystic spaces were sometimes present. These cystic cavities contained an eosinophilic material which was faintly PAS positive. The epithelial cells were columnar or cuboidal in shape, with a scant eosinophilic cytoplasm. Those cells which made up the tubular or trabeeular portion of the neoplasm were either arranged in a palisading fashion or pseudostratified (Fig. 2). The nuclei in these cells were elongated, and nucleoli were sometimes noted. The cells which composed the solid nests were cuboidal and contained ovoid nuclei. The cells at the periphery of these solid nests were similar in shape to those that composed the tubular or trabecular pattern (Fig. 3). Mitotic figures were absent.
436
Fantasia and Neville
Oral Surg. November. 1980
Fig. 2. Photomicrograph demonstrating uniform basaloid cells with elongated nuclei. Note the delicate vascular network which is closely associated with the neoplastic epithelium. (Hematoxylin and eosin stain. Original magnification, × 240.)
Fig. 3. Photomicrograph demonstrating solid nests of basaloid epithelial cells, although occasional small ductlike spaces are present. Note the peripheral palisading around each group of cells. (Hematoxylin and eosin stain. Original magnification, x 160.)
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Basal cell adenomas of minor salivary glands
437
Fig, 4. Microscopic section which exhibits a solid sheet of basaloid epithelial cells. Adjacent areas demonstrated the more common tubulotrabecular pattern. (Hematoxylin and eosin stain. Original magnification, × 200~ ', The stroma consisted of loose connective tissue which contained a delicate vascular network (Fig. 2). The tumors were surrounded by a fibrous connective tissue capsule; nests of tumor ceils were sometimes present in this capsule. Proliferative changes of minor salivary gland ducts were noted occasionally in tissue adjacent to the main tumor mass. These ductal changes consisted of stratified squamous and mucous metaplasia (Fig. 5). Also noted in one case were a microscopic adenomatous focus within the surrounding normal glandular tissue and proliferative duct changes (Fig. 6).
DISCUSSION The basal cell adenoma has been reported under a variety of names. 5 Terms such as tubular, canalicular, trabecular, and solid have been used to further describe these neoplasms. These terms may be used alone or in combination to designate the predominating pattern(s). We agree with Waldron 22 that the designation basal cell adenoma is probably the most inclusive term, with these modifying terms used to represent architectural variations (for example, basal cell adenoma-tubular type). We assume that the terms canalicular and tubular are synonymous. The most striking clinical finding is the predilection for this lesion to occur in the upper lip or adjacent tissues. In all seventeen of our cases the tumors were found in this location. When our cases were combined
with those previously reported in the literature, we found that 80 percent occurred in this location. Also of interest was the clinician's presumptive diagnosis of mucocele in many of the cases. Large cystic spaces were a common finding in the BCAs that we examined, and it is not surprising that this feature would lead one to consider a diagnosis of mucocele. It is our experience that mucoceles most commonly involve the lower lips of young patients (second and third decades), whereas the BCA typically occurs in older patients (mean age, 61 years) and, as stated, usually involves the upper lip. On the basis of these clinical data, the BCA should therefore he included in the differential diagnosis of a submucosal mass within or adjacent to the upper lip in an older patient. The BCA has sometimes been mistaken for adenoid cystic carcinoma. The two distinguishing features which help separate these lesions are (1) the circumscription of the BCA versus the invasive pattern of the adenoid cystic carcinoma and (2) the lack of vascularity in the mierocystic areas of adenoid cystic carcinoma, which contrasts with the numerous endothelium-lined channels seen in the BCA. 1~ Some authors suggest that the BCA is the benign counterpart of the adenoid cystic carcinoma. 6 Reports of BCA and adenoid cystic carcinoma occurring in the same neoplasm have supported this hypothesis. 3' 7 We can find no evidence to support this theory. If the BCA
438 Fantasia and Neville
Oral Surg. November, 1980
Fig. 5. Photomicrograph demonstrating squamous and mucous metaplasia of a salivary gland duct (top center) located in the capsule surrounding a basal cell adenoma. (Hematoxylin and eosin stain. Original magnification,
x64.)
FiO. 6. Photomicrograph of changes seen in otherwise normal minor salivary gland tissue adjacent to a basal cell adenoma. Note the proliferation of basal cells which surround an interlobular duct (arrows). Also present is a micro-adenomatous focus in the lower right quadrant. Note the similar histologic features of the cells which comprise the micro-adenomatous focus and the proliferating cells that surround the salivary gland duct. (Hematoxylin and eosin stain. Original magnification, x240.)
Volume 50 Number 5 were the benign counterpart of the adenoid cystic carcinoma, one would also expect to find a high number of adenoid cystic carcinomas in the upper lip. However, the upper lip is an unusual site for adenoid cystic carcinomas.23, 24 Conversely, relatively few B C A s were found in the palate, which is the most c o m m o n site for intraoral adenoid cystic carcinomas. H a m s o n 16 performed extensive mucosubstance and enzyme histochemistry studies on a B C A of minor gland origin. He concluded that the " t u m o r cells show histochemical similarities to myoepithelial cells and to ductal cells lining l u m i n a . " He suggested the term cystic adenoma as being a more appropriate name. However, electron microscopic studies by Luna and Mackay 6 noted the absence of myoepithelial cells in a B C A of the parotid gland. This finding has also been reported by Hiibner and associates 4 and b y Min and colleagues.5 Chen and Miller, 25 who performed electron microscopic studies o f BCAs of minor glands, also noted the absence o f myoepithelial cells. Other ultrastructural observations in these studies include the presence of a well-defined basal lamina located at the periphery o f the tumor cell groups and extending into the adjacent stroma.~, 6 Secretory granules were noted in some of the tumor cells. ~ Eversole 26 suggested that the B C A represented a hamartomatous transformation o f intercalated duct cells. Although electron microscopic studies o f a parotid B C A by Headington and associates 27 supported this postulate, they could neither confirm nor exclude an intercalated duct cell origin. The tumor studied by Headington and associates 2~ was a membranous B C A . Those authors separate the membranous B C A from the classic BCA, based on the finding of abundant hyaline membrane material. They also comment on the morphologic similarity between the membranous B C A and the dermal cylindroma. These two lesions (membranous B C A and dermal cylindroma) have been reported occurring in the same patient. 27, 28 The membranous B C A has been reported only in the parotid. 29 None of our minor gland B C A s exhibited the pattern o f the membranous BCA. Proliferation of basal cells along an interlobular duct o f otherwise normal glandular tissue adjacent to a B C A (Fig. 6) suggests that these tumors may arise from such cells. Therefore, the possibility that B C A s arise from basal cells anywhere along the salivary duct system (intercalated, striated, or excretory duct) cannot be discounted.
SUMMARY Seventeen new cases of basal cell adenoma of minor salivary glands have been reported and the literature has been reviewed. The tumors occurred most fre-
Basal cell adenomas of minor salivary, glands
439
quently in or near the upper lip (80 percent) and were usually found in middle-aged and older persons (mean age, 61 years). No recurrences were noted in those cases for which follow-up information was available (mean follow-up period, 27.3 months). The microscopic features and histogenesis of these tumors have been discussed briefly. The authors wish to thank Susan Tuttle and Beverly Maleeff for technical assistance and Susan Hill for preparing the manuscript.
REFERENCES 1. Willis, R. A.: Pathology of Tumours. ed. 4, London, 1967, Butterworth & Co., Ltd., p. 319. 2. Kleinsasser, O., and Klein, H. J.: Basalzelladenome der Speicheldriisen, Arch. Klin. Exp. Ohr. Nas. Kehlkoptheilkd. 189: 302-316, 1967. 3. Evans, R. W., and Cruickshank, A. H. : Epithelial Tumours of the Salivary Glands, Philadelphia, 1970, W. B. Sannders Company, pp. 58-76. 4. H/ibner, G., Kleinsasser, O., and Klein, H. J.: Zur Feinstruktur der Basalzelladenome der Speicheldr/isen, Virchows Arch. [Pathol. Anat.] 353: 333-346, 1971. 5. Min, B. H., Miller, A. S., Leifer, C., and Putong, P. B.: Basal Cell Adenoma of the Parotid Gland, Arch. Otolaryngol. 99: 88-93, 1974. 6. Luna, M. A., and Mackay, B.: Basal Cell Adenoma of the Parotid Gland: Case Report With Ultrastructural Observations, Cancer 37: 1615-1621, 1976. 7. Bernacki, E. G., Batsakis, J. G., and Johns, M. E.: Basal Cell Adenoma: Distinctive Tumor of Salivary Glands, Arch. Otolaryngol. 99: 84-87, 1974. 8. Eggers, H. E.: Mixed Tumors of the Palate, Arch. Pathol. 6: 378-395, 1928. 9. Bhaskar, S. N., and Weinmann, J. P.: Tumors of the Minor Salivary Glands, ORALSURG. 8: 1278-1297, 1955. 10. Davis. W. M., and Davis, W. M., Jr.: Canalicular Adenoma: Report of Case, J. Oral Surg. 29:. 500-501, 1971. 11. Christ, T. F., and Crocker, D.: Basal Cell Adenoma of Minor Salivary Gland Origin, Cancer 30: 214-219, 1972. 12. Klein, H. Z., and Goldman, R. L.: Basal Cell Adenoma Involving the Lip, Arch. Pathol. 95: 94-96, 1973. 13. Bollinger, T. E., and Hiatt, W. R.: Basal-cell Adenoma of the Upper Lip: Report of a Case, ORALSURG.35: 600-605, 1973. 14. Nelson, J. F., and Jacoway, J. R.: Monomorphic Adenoma (Canalicular Type): Report of 29 Cases, Cancer 31:1511-1513, 1973.
15. Kerr, S. : Pleomorphic Salivary Adenoma of the Lower Lip: A Rare Site of Occurrence, Med. J. Aust. 2: 251, 1974. 16. Harrison, J. D.: Cystic Adenoma of a Minor Salivary Gland: A Histochemical Study, J. Pathol. 114: 29-38, 1974. 17. Strychalski, J.: Basal Cell Adenoma of Intraorat Minor Salivary Gland Origin, J. Oral Surg. 32: 595-600, 1974. 18. Crumpler, C., Scharfenberg, J. C., and Reed, R. J.: Monomorphic Adenomas of Salivary Glands: Trabecular-Tubular, Canalicular, and Basaloid Variants, Cancer 38: 193-200, 1976. 19. Ahrrn, C., and Lindstrrm, J.: Adenomatosis of Accessory Salivary Glands of the Lip: Report of Two Cases, ORL 39: 161-166, 1977. 20. Wiener, A. P.: Monomorphic Adenoma, Canalicular Variant: Report of Case, J. Oral Surg. 35: 414-415, 1977. 21. Frim, S. P., and Giunta, J.: Monomorphic Adenoma (Basal Cell Adenoma): Report of Case, J. Oral Surg. 37: 426-427, 1979. 22. Waldron, C. A.: Comment, J. Oral Surg. 29: 502, 1971. 23. Chaudhry, A. P., Vickers, R. A., and Gorlin, R. J.: Intraoral Minor Salivary Gland Tumors: An Analysis of 1,414 Cases, ORAL SURG. 14: 1194-1226, 1961.
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24. Tarpley, T. M., and Giansanti, J. S.: Adenoid Cystic Carcinoma; Analysis of Fifty Oral Cases, ORAL SURG. 41: 484-497, 1976. 25. Chen, S. Y., and Miller, A. S.: Canalicular Adenoma of the Upper Lip: An Electron Microscopic Study, Cancer 46: 552556, 1980. 26. Eversole, L. R.: Histogenic Classification of Salivary Tumors, Arch. Pathol. 92: 433-443, 1971. 27. Headington, J. T., Batsakis, J. G., Beals, T. F., Campbell, T. E., Simmons, J. L., and Stone, W. D.: Membranous Basal Cell Adenoma of Parotid Gland, Dermal Cylindromas, and Trichoepitheliomas: Comparative Histochemistry and Ultrastructure, Cancer 39: 2460-2469, 1977.
Oral Surg. November, 1980 28. Reingold, 1. M., Keasbey, L. E., and Graham, J. H.: Multicentric Dermal-type Cylindromas of the Parotid Glands in a Patient With Florid Turban Tumor. Cancer 40: 1702-1710. 1977. 29. Batsakis, J. G.: Tumors of the Head and Neck, ed. 2, Baltimore, 1979, Williams & Wilkins Company, p. 50.
Reprint requests to: Dr. John E. Fantasia Pathology Department Temple University School of Dentistry 3223 North Broad St. Philadelphia, Pa. 19140
I
[
II
I
Basal cell adenomas of the minor salivary glands A clinicopathologic study of seventeen new cases and a review of the UterabJre John E. Fantasia, D.D.S.,* and Brad W. Neville, D.D.S., ** Philadelphia, Pa., and Atlanta, Ga. TEMPLE
UNIVERSITY
SCHOOL
OF DENTISTRY
AND EMORY
UNIVERSITY
SCHOOL
OF DENTISTRY
The basal cell adenoma (BCA) is a benign monomorphic salivary gland tumor. Those of minor gland origin tend to occur within or adjacent to the upper lip (80 percent). The BCA is an encapsulated, slow-growing lesion which most commonly affects older persons. Several different histologic patterns can be noted, and often a combination of these variations is present within the same tumor. Simple surgical excision appears to be adequate treatment.
T h e salivary gland basal cell adenoma (BCA) is an unusual type of monomorphic adenoma which occurs in both the major and minor glands. These lesions appear to have certain distinct clinical and pathologic features. Historically, BCAs were once considered a variant of the benign mixed tumor. 1 More recently, Kleinsasser and Klein 2 and Evans and Cruickshank 3 have defined and separated this isomorphic epithelial tumor from the benign mixed tumor. The lack of both myoepithelial cells and myxochondroid elements distinguishes the BCA from mixed salivary gland tumors. 2 Electron microscopic studies by Hiibner and associates, 4 Min and colleagues, 5 and Luna and Mackay 6 have confirmed the absence of myoepithelial cells in this tumor. Basal cell adenomas of the major salivary glands occur most frequently in the parotid gland. 7 The present report deals with the clinical and pathologic features of BCAs of the minor salivary glands of the oral cavity. MATERIALS AND METHODS
Seventeen minor salivary gland BCAs from the files of the Departments of Oral Pathology of the Temple University and Emory University Schools of Dentistry
This study was supported in part by Grant No. CA19456-04 and Fellowship Grant No. 19253-04 from the National Cancer Institute, Bethesda. Md. *Assistant Professor, Departmentof Pathology, Temple University School of Dentistry. **Clinical OncologyFellow, Departmentof Oral Pathology, Emory University School of Dentistry. 0030-4220/80/110433+08500.80/0
(~) 1980 The C. V. Mosby Co.
were studied with the light microscope. The clinical data were also tabulated. A preliminary analysis comparing the clinical data of our seventeen cases with previous reports of BCAs of the minor glands revealed no significant differences. These cases were combined, yielding a total of seventy for analysis. REVIEW OF THE LITERATURE
Table I represents those cases obtained from a review of the literature, with the available clinical data. Eggers, s in 1928, reported on mixed tumors of the palate. However, in two of his cases (Nos. 6 and 7), he noted "the conspicuous absence of mucoid connective tissue and cartilage." He did not include these cases in his series of benign mixed tumors but simply referred to them as " a d e n o m a s . " The photomicrographs show acceptable BCAs, and therefore they are included in this review. In 1967 Kleinsasser and Klein 2 reported a series of BCAs, including one of minor salivary gland origin. Christ and Crocker, 11 in a review of BCAs of minor glands, included three cases of their own along with previously published cases by Bhaskar and Weinmann, 9 Evans and Cruickshank, 3 and Davis and Davis. 10 Klein and Goldman ~2 reported one case in 1973. In an addendum to their article, they mentioned the occurrence of another BCA in the buccal mucosa of a 74year-old woman. Both of these cases are included in Table I. Nelson and Jacoway 14 reported the largest series of BCAs, consisting of twenty-nine cases which they
434
Fantasia and Neville
Oral Surg. N o v e m b e r , 1980
Table I. Reported cases of basal cell adenoma Location No.
Adjacent upper
of Author
cases
Age
Sex
Race
Upper lip
Lip, not
lip
L o w e r lip
.
4 1
--
--
2
1
1
65
M
--
Evans and Cruickshank a
2
40
F
--
56
F
--
1
3
1
--
--
1
--
1
87
M
W
l
Christ and Crocker 1~
3
56
M
W
l
60
F
W
1
78
M
W
1
59
M
W
1
74
F
--
73
M
W
Mean,
16M
17W
23
60
13F
Nelson and Jacoway 14
1 28
-1
Kerr 15
1
41
M
--
--
Harrison TM
1
51
F
--
--
S t r y c h a l s k i iv
1
71
F
W
1
Crumpler et at. is Ahren and Lindstrom ~
2 60
M
--
l
64
M
--
l
2
.
.
Wiener 2°
1
67
F
B
1
F i l m and Giunta 21
l
71
F
W
l
17
Mean,
l IF
14W
14
3
61
6M 32F 31M
IB 39W 2B
50
6
Fantasia and Neville Total
70
Mean, 61
2
1
Davis and Davis l°
Bollinger and Hiatt 13
.
Palate
2
2
.
Buccal mucosa
Eggers s Bhaskar and W e i n m a n n a Kleinsasser and Klein 2
Klein and Goldman TM
.
specified
termed monomorphic adenoma, canalicular type. One case was from the parotid gland; therefore, it was deleted from their total number of cases. However, we did use their clinical data as they presented it, aware that the one parotid lesion is reflected in these data. In 1974 H a r r i s o n 16 performed histochemical studies on a BCA o f the buccal mucosa. Kerr ~5 reported the occurrence of a pleomorphic salivary adenoma in the lower lip. Examination of the photomicrograph suggests that this is a BCA, and it is included as such. Crumpler and associates ~8 reported eleven cases of
.
.
.
2
.
2
.
3
.
3
6
BCA, two of which arose from minor salivary gland tissue. Wiene:a° reported what appears to be the first case in a non-Caucasian. Additional case reports by Bollinger and Hiatt, la Strychalski, 17 Ahr6n and Lindstr6m, la and Frim and Giunta 21 are also listed.
CLINICAL FEATURES The patient's age was available in sixty-two of the seventy cases. The age range was from 33 to 87 years, with a mean age of 61 years. The location was stated in all seventy cases. Fifty
Volume 50 Number 5
Basal cell adenomas of minor salivary glands
435
Fig. 1. Low-power photomicrograph demonstrating a tubular and trabecular architecture. Note the fibrous connective tissue capsule. (Hematoxylin and eosin stain. Original magnification, ×40.) occurred in the upper lip, six were adjacent to the upper lip, two were found in the lower lip, and three were present within the lips but the specific location was not stated, three occurred in the buccal mucosa, and six were present on the palate. Fifty-six cases (80 percent) occurred within or adjacent to the upper lip. There was no sex predilection. The patient's sex was known in sixty-three cases, with thirty-two of the tumors occurring in women and thirty-one occurring in men. The patient's race was known in forty-one cases. Thirty-nine patients were white and two patients were black. Follow-up information was available in fourteen of our seventeen cases. The range was from 1 to 48 months, with a mean follow-up of 17.3 months. Recurrence has not been noted in any of these cases. Of the fifty-three cases reviewed from the literature, follow-up information was provided in thirty, with no recurrences reported. Follow-up ranged from 2 to 128 months with a mean follow-up of 32 months. Combining our cases with those from the literature, follow-up information is available on forty-four of seventy cases, with no recurrences noted. Follow-up ranges from 1 month to 128 months, with a mean of 27.3 months. Additional clinical data from our seventeen cases follow. Four of the seventeen were described as painful. Surgical excision was the mode of treatment in all
seventeen cases. The most common clinical diagnosis was mucocele, which was rendered in nine cases. Other diagnoses included in the clinicians' differentials were sebaceous cyst, nasolabial cyst, thrombosed oral varix, lipoma, and salivary gland tumor.
MICROSCOPIC FEATURES These neoplasms consisted of basaloid epithelial cells which were most commonly arranged in a tubular and/or tmbecular pattern (Figs. 1 and 2). Solid nests or sheets of cells were occasionally noted (Figs. 3 and 4). The tumors frequently exhibited a combination of the different patterns, with one of the patterns (tubular, trabecular, or solid) usually predominating. Large cystic spaces were sometimes present. These cystic cavities contained an eosinophilic material which was faintly PAS positive. The epithelial cells were columnar or cuboidal in shape, with a scant eosinophilic cytoplasm. Those cells which made up the tubular or trabeeular portion of the neoplasm were either arranged in a palisading fashion or pseudostratified (Fig. 2). The nuclei in these cells were elongated, and nucleoli were sometimes noted. The cells which composed the solid nests were cuboidal and contained ovoid nuclei. The cells at the periphery of these solid nests were similar in shape to those that composed the tubular or trabecular pattern (Fig. 3). Mitotic figures were absent.
436
Fantasia and Neville
Oral Surg. November. 1980
Fig. 2. Photomicrograph demonstrating uniform basaloid cells with elongated nuclei. Note the delicate vascular network which is closely associated with the neoplastic epithelium. (Hematoxylin and eosin stain. Original magnification, × 240.)
Fig. 3. Photomicrograph demonstrating solid nests of basaloid epithelial cells, although occasional small ductlike spaces are present. Note the peripheral palisading around each group of cells. (Hematoxylin and eosin stain. Original magnification, x 160.)
Volume 50 Number 5
Basal cell adenomas of minor salivary glands
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Fig, 4. Microscopic section which exhibits a solid sheet of basaloid epithelial cells. Adjacent areas demonstrated the more common tubulotrabecular pattern. (Hematoxylin and eosin stain. Original magnification, × 200~ ', The stroma consisted of loose connective tissue which contained a delicate vascular network (Fig. 2). The tumors were surrounded by a fibrous connective tissue capsule; nests of tumor ceils were sometimes present in this capsule. Proliferative changes of minor salivary gland ducts were noted occasionally in tissue adjacent to the main tumor mass. These ductal changes consisted of stratified squamous and mucous metaplasia (Fig. 5). Also noted in one case were a microscopic adenomatous focus within the surrounding normal glandular tissue and proliferative duct changes (Fig. 6).
DISCUSSION The basal cell adenoma has been reported under a variety of names. 5 Terms such as tubular, canalicular, trabecular, and solid have been used to further describe these neoplasms. These terms may be used alone or in combination to designate the predominating pattern(s). We agree with Waldron 22 that the designation basal cell adenoma is probably the most inclusive term, with these modifying terms used to represent architectural variations (for example, basal cell adenoma-tubular type). We assume that the terms canalicular and tubular are synonymous. The most striking clinical finding is the predilection for this lesion to occur in the upper lip or adjacent tissues. In all seventeen of our cases the tumors were found in this location. When our cases were combined
with those previously reported in the literature, we found that 80 percent occurred in this location. Also of interest was the clinician's presumptive diagnosis of mucocele in many of the cases. Large cystic spaces were a common finding in the BCAs that we examined, and it is not surprising that this feature would lead one to consider a diagnosis of mucocele. It is our experience that mucoceles most commonly involve the lower lips of young patients (second and third decades), whereas the BCA typically occurs in older patients (mean age, 61 years) and, as stated, usually involves the upper lip. On the basis of these clinical data, the BCA should therefore he included in the differential diagnosis of a submucosal mass within or adjacent to the upper lip in an older patient. The BCA has sometimes been mistaken for adenoid cystic carcinoma. The two distinguishing features which help separate these lesions are (1) the circumscription of the BCA versus the invasive pattern of the adenoid cystic carcinoma and (2) the lack of vascularity in the mierocystic areas of adenoid cystic carcinoma, which contrasts with the numerous endothelium-lined channels seen in the BCA. 1~ Some authors suggest that the BCA is the benign counterpart of the adenoid cystic carcinoma. 6 Reports of BCA and adenoid cystic carcinoma occurring in the same neoplasm have supported this hypothesis. 3' 7 We can find no evidence to support this theory. If the BCA
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Fig. 5. Photomicrograph demonstrating squamous and mucous metaplasia of a salivary gland duct (top center) located in the capsule surrounding a basal cell adenoma. (Hematoxylin and eosin stain. Original magnification,
x64.)
FiO. 6. Photomicrograph of changes seen in otherwise normal minor salivary gland tissue adjacent to a basal cell adenoma. Note the proliferation of basal cells which surround an interlobular duct (arrows). Also present is a micro-adenomatous focus in the lower right quadrant. Note the similar histologic features of the cells which comprise the micro-adenomatous focus and the proliferating cells that surround the salivary gland duct. (Hematoxylin and eosin stain. Original magnification, x240.)
Volume 50 Number 5 were the benign counterpart of the adenoid cystic carcinoma, one would also expect to find a high number of adenoid cystic carcinomas in the upper lip. However, the upper lip is an unusual site for adenoid cystic carcinomas.23, 24 Conversely, relatively few B C A s were found in the palate, which is the most c o m m o n site for intraoral adenoid cystic carcinomas. H a m s o n 16 performed extensive mucosubstance and enzyme histochemistry studies on a B C A of minor gland origin. He concluded that the " t u m o r cells show histochemical similarities to myoepithelial cells and to ductal cells lining l u m i n a . " He suggested the term cystic adenoma as being a more appropriate name. However, electron microscopic studies by Luna and Mackay 6 noted the absence of myoepithelial cells in a B C A of the parotid gland. This finding has also been reported by Hiibner and associates 4 and b y Min and colleagues.5 Chen and Miller, 25 who performed electron microscopic studies o f BCAs of minor glands, also noted the absence o f myoepithelial cells. Other ultrastructural observations in these studies include the presence of a well-defined basal lamina located at the periphery o f the tumor cell groups and extending into the adjacent stroma.~, 6 Secretory granules were noted in some of the tumor cells. ~ Eversole 26 suggested that the B C A represented a hamartomatous transformation o f intercalated duct cells. Although electron microscopic studies o f a parotid B C A by Headington and associates 27 supported this postulate, they could neither confirm nor exclude an intercalated duct cell origin. The tumor studied by Headington and associates 2~ was a membranous B C A . Those authors separate the membranous B C A from the classic BCA, based on the finding of abundant hyaline membrane material. They also comment on the morphologic similarity between the membranous B C A and the dermal cylindroma. These two lesions (membranous B C A and dermal cylindroma) have been reported occurring in the same patient. 27, 28 The membranous B C A has been reported only in the parotid. 29 None of our minor gland B C A s exhibited the pattern o f the membranous BCA. Proliferation of basal cells along an interlobular duct o f otherwise normal glandular tissue adjacent to a B C A (Fig. 6) suggests that these tumors may arise from such cells. Therefore, the possibility that B C A s arise from basal cells anywhere along the salivary duct system (intercalated, striated, or excretory duct) cannot be discounted.
SUMMARY Seventeen new cases of basal cell adenoma of minor salivary glands have been reported and the literature has been reviewed. The tumors occurred most fre-
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quently in or near the upper lip (80 percent) and were usually found in middle-aged and older persons (mean age, 61 years). No recurrences were noted in those cases for which follow-up information was available (mean follow-up period, 27.3 months). The microscopic features and histogenesis of these tumors have been discussed briefly. The authors wish to thank Susan Tuttle and Beverly Maleeff for technical assistance and Susan Hill for preparing the manuscript.
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