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Ameloblastomas associated with dentigerous cysts
oral pathology Editor: CHARLES
E. TOMICH,
D.D.S., M.S.D.
American Academy of Oral Pathology Indiana Universi~ School of Dentist0 l/2/ West Michigan Street Indianapolis, Indiana 46302
Short communications & case reports Ameloblastomas associated with dentigerous cysts M. D. McMillan. DEPARTMENT
M.D.S., Ph.D. I and A. C. Smillie, M.D.S., Ph.D., Dunedin, New Zealand
OF ORAL
BIOLOGY,
SCHOOL
OF DENTISTRY,
UNIVERSITY
Five cases of ameloblastoma apparently arising in the walls of dentigerous Evidence supporting this concept is discussed.
T
he apparent development of ameloblastoma in the wall of a dentigerous cyst was first described by Cahn’ in 1933. Since that time, many such casks have been recorded. Sonesson,2 in reporting thirty-nine cases of ameloblastoma, considered that at least ten of these had arisen from odontogenic cysts, while Bemier and Tiecke3 state that approximately 33 Percent of the eighty-eight ameloblastomas in their series arose in follicular cysts (dentigerous cysts). In 1965, Stanley and Diehl” reviewed the English-language publications and found 446 cases of ameloblastoma. They added 193 cases from the Armed Forces Institute of Pathology and two cases from the National Institutes of Health, making a total of 641 cases. Of these 641 cases, 108 were said to be definitely associated with an impacted tooth .and/or a follicular cyst (dentigerous cyst). Meyer,j in comments on a reported case of an ameloblastoma arising in the wall of a dentigerous cyst, stated that in a 25year Period at the Tufts University School of Dental Medicjne, twenty-five ameloblastomas had been diagnosed. Over the same perioq, 500 dentigerous cysts were examined and, of these, only four showed ameloblastomatous changes in their walls. In spite of the large number of reports of ameloblastic change in the walls of dentigerous cysts, Lucas’
0030-4220/81/050489+08500.80/0
@
1981
‘he C. V. Mosby Co.
OF OTAGO
cysts are presented.
points out that the evidence is somewhat equivocal, as in many of the reports no definite evidence is offered to show that a neoplasm has developed from what was previously a simple cyst. The purpose of this study is to present five cases in which an ameloblastoma appears to be arising in the wall of a dentigerous cyst and to draw attention to data supporting this possibility. CASE 1
A 21-year-old man presentedwith a swelling of the left side of the face. Radiographic examination revealed a large, well-defined, unilocular radiolucency associatedwith an unerupted third molar. Gross examination failed to reveal any obvious mural thickening. Histologically, the cyst cavity was lined in part with degenerate stratified squamous epithelium infiltrated with inflammatory cells (Fig. 1). Elsewhere, the cyst cavity was not lined with epithelium. The bulk of the cyst wall consisted of a relatively acellular, dense, fibrous connective tissue. In someplaces, the epithelial lining liad a more odontogenic appearance.Islands of odontogenic-appearing epithelium were found in the adjacent connective tissue. These epithelial @landsconsistedof a peripheral layer of cuboidal to low-columnar cells which surroundedmore stellate cells and frequently showed cystic degeneration(Fig. 2). 489
490
MrMillan
and Smillie
Oral Surg. May, 1981
Fig. 1. Case 1. Photomicrograph of the thin epithelial lining (arrows) and inflamed connective tissue (A) forming the cyst wall. (Hematoxylin and phloxine stain. Magnification, x220.)
Fig. 2. Case 1. Photomicrograph of cyst wall showing ameloblastomatous epithelial islands composed of a peripheral layer of cuboidal or columnar cells (arrows) surrounding more stellate cells (S) Note areas of cystic degeneration (arrou+zeads). (Hematoxylin and phloxine stain. Magnification, x 110.)
Volume 5 1 Number 5
Ameloblastomas associated lcith dentigerous c,ysts 497
Fig. 3. Case 2. Radiograph showing well-defined unilocular
Fig. 4. Case 2. Radiograph of fixed pathology specimen show-
radiolucency (RJ involving the ramus and body of the left mandible. Note root resorption (arrow).
ing cyst cavity (C), two mural thickenings (M), and root resorption (nrro\~)
CASE 2
the soft-tissue projection, the epithelial lining had a more odontogenic appearance (Fig. 7). This odontogenic epithelium was continuous with sheets and strands of similarappearing epithelium present within the soft-tissue projection and extending deeply into the connective tissue of the cyst wall. Cystic areas were found within both the epithelial sheets and the connective tissue. However. the epithelium lining these small cysts was ameloblastomatous in appearance, with cuboidal or columnar basal cells, thus contrasting sharply with the stratified squamous epithelium which lined the large cyst cavity.
A 12-year-old boy presented with a swelling of the left side of the mandible. Radiographic examination revealed a well-demarcated unilocular radiolucency associated with an unerupted second molar (Fig. 3). The roots of the first permanent molar, which were also associated with the radiolucency, showed obvious resorption. Radiographic and gross examination of the specimen revealed that the crown of the second molar appeared to be in the cyst cavity (Fig. 4). Two mural outgrowths extended into the cyst cavity. Histologic examination of the area which contained the second molar revealed that the reduced enamel epithelium was continuous with, and formed part of, the epithelial lining of the cyst cavity (Fig. 5). This epithelium was, in the main, only two to three cells thick and there was no evidence of keratinization. In the areas of the two gross mural thickenings, proliferation of epithelium and of a delicate connective tissue was found. This epithelium was continuous with that lining the cyst, and it consisted of sheets and strands of cells that had an odontogenic appearance (Fig. 6). Histologic examination of the first molar confirmed that resorption of the roots had occurred. CASE 3
A 15year-old girl presented with an acute painful swelling that had developed in the left mandibular molar region 4 weeks previously. Radiographic examination revealed a large, well-defined, unilocular radiolucency associated with an unerupted second molar. The roots of the erupted first molar were also associated with the radiolucency and showed resorption. Grossly, a solid mass of tissue was found extending between the crown of the second molar and the wall of the cyst to which it was attached. Histologically, the cyst wall consisted of a thin, stratified, squamous epithelium with a thick backing of dense fibrous connective tissue. In many areas, a moderate infiltration of lymphocytes and plasma cells was present in the connective tissue immediately beneath the epithelium. In the vicinity of
CASE 4
A 14-year-old boy presented with a painful swelling on the left side of the face. Radiographic examination revealed a unilocular, well-circumscribed radiolucency associated with unerupted second and third molars. Both the erupted first molar and second premolar showed evidence of root resorption. Histologically, the wall of the cyst consisted of stratified squamous epithelium which, in places, showed hyperplasia with elongation of the rete pegs, supported by a thick and cellular connective tissue. There was a moderate infiltration of lymphocytes and plasma cells adjacent to much of this epithelium (Fig. 8). In one area the epithelium had a more odontogenic appearance, and in the associated connective tissue there were many epithelial islands and cords, some of which showed cystic degeneration (Fig. 9). The reduced enamel epithelium was continuous with the epithelium which lined the cyst. CASE 5
A 12-year-old boy presented with an asymptomatic right facial swelling. Radiographic examination revealed a large, well-circumscribed, unilocular radiolucency associated with an unerupted third molar. The roots of the involved first molar showed resorption. Six days prior to operation, an episode of acute inflammation occurred. Histologically, the bulk of the cyst cavity was lined with a
492
McMillan
and Smillie
Oral Surg. May. 19sl
Fig. 5. Case 2. Photomicrograph through a section which includes the unerupted second molar(T) . Note reduced enamel epithelium (arrows). which was continuous with the cyst lining, and enamel space (E). (Hematoxylin and phloxine stain. Magnification, X40.)
Fig. 6. Case 2. Photomicrograph in area of the smaller mural thickening showing cyst cavity (Cj; thin epithelium lining cyst (arrows); strands and sheets of ameioblastomatous epithelium (arrowheads). (Hematoxylin and phloxine stain. Magnification, x40.)
Volume 5 I Number 5
Ameloblastomas
associated
with dentigerous
cysts
Fig. 7. Case 3. Photomicrograph through cyst cavity (C) showing the lining of stratified squamous epithelium (arron~s) and area of ameloblastomatous epithelium (A). (Hematoxylin and phloxine stain. Magnification, X 40.)
Fig. 8. Case 4. Photomicrograph of the wall of the cyst showing stratified squamous epithelium (arrows) and inflame’d connective tissue (C). (Hematoxylin and phloxine stain. Magnification, x ZOO.)
493
494
McMillan
and Smillie
Oral Surg. blay, 1981
Fig. 9. Case 4. Photomicrograph showing ameloblastomatous epithelium (E) in the wall of the cyst. (Hematoxylin and phloxine stain. Magnification, x40.)
stratified squamous epithelium which was supported by a thick layer of dense connective tissue (Fig. 10). In places, the epithelial lining was absent. A mixed inflammatory cell infiltration was found throughout most of the connective tissue of the cyst wall. In places, the epithelial lining was more odontogenic in appearance and marked proliferation of the epithelium into the underlying connective tissue was found. These deeper epithelial elements consisted of cords and islands of ameloblastomatous-appearing epithelium (Fig. 11).
DISCUSSION All the lesions were diagnosed initially as dentigerous cysts on the basis of their radiographic appearances. This emphasizes the necessity of submitting all dentigerous cysts for histopathologic examination. In a review of 1,036 cases of ameloblastoma, Small and Waldron’ report that the average age of patients seeking treatment was 38.9 years, while the average age at which symptoms from the lesion were first noted was 32.7 years. All the lesions in the present study were from considerably younger patients. Stanley and Diehl,4 from a study of 108 cases of ameloblastomas associated with demigerous cysts and/or impacted teeth, report that the average age at diagnosis was 21 years. This is 18 years earlier than that for the diagnosis of all types of ameloblastomas.7 Since the review by Stanley and Diehl,’ only a small number of reports of
ameloblastomas associated with dentigerous cysts have appeared in the literature. A critical evaluation of these reports shows that the great majority of the patients were in the 6 to 14-year age group.*-” Dentigerous cysts themselves are generally detected in children or adolescents .6 The considerably earlier age for the clinical presentation of ameloblastomas associated with dentigerous cysts as opposed to ameloblastomas in general offers support for the concept that ameloblastomas can arise in the walls of dentigerous cysts. This is contrary to the suggestion that such lesions are ameloblastomas which have undergone cystic degeneration, with the coalescence of numerous small cysts to form one large one. If the latter process took place, it would be reasonable to suggest that such lesions would be found in the age group that includes ameloblastomas in general and not in a younger group. Small and Waldron7 have stated that all ameloblastomas begin as solid tumors and gradually become more cystic with age. This could well apply to ameloblastomas arising from dentigerous cysts. The present findings support this, as cyst formation was present in all five ameloblastomas reported here. In our experience, the stroma of uncomplicated ameloblastomas is not infiltrated by inflammatory cells.
Volume 5 I Number 5
Atneloblastot~asassociated with detttigerous qsts
495
Flg. 10. Case 5. Photomicrograph of cyst wall showing stratified squamous epithelium (E) and inflamed connective tissue (CJ. (Hematoxylin and phloxine stain. Magnification, x 220.)
whereas that of dentigerous cysts often is. This experience would appear to be shared by others.“, I3 In all cases described in the present report, varying numbers of inflammatory cells were found in the wall of the cyst. This can be interpreted as evidence that the major cystic lesion is a dentigerous cyst. The findings in Cases 2 and 4 that the reduced enamel epithelium which surrounded the crown of the impacted tooth was continuous with that lining the large cyst cavity is further evidence that these lesions were initially dentigerous cysts. Because of the nature of the material submitted for histologic examination in the other three cases, this aspect of these lesions, unfortunately, could not be evaluated. In each of the cases presented in this report, the epithelium lining the large cyst changed from a stratified squamous epithelium to one having a markedly odontogenic appearance in the region of the ameloblastomatous tissue. The lining epithelium was always continuous with that forming the ameloblastoma, irrespective of whether the ameloblastoma was found in the cyst wall proper or as a projection into the cyst lumen. This finding supports the suggestion that the arneloblastoma arose by transformation of the epithelial lining of the cyst.14 Following a histologic study of 10 jaw cysts and an analysis of the literature, Vickers and Gorlin” concluded that cysts which showed areas of epithelium with hyperchromatism of basal cell nuclei, palisading with polarization of the basal cells, and cytoplasmic vacuolization of (especially) basal cells with intercellu-
lar spacing were associated with ameloblastoma in a high percentage of cases. All the examples in the present report exhibited hyperchromatism of basal cell nuclei and palisading with polarization of the basal cells in areas of cyst lining which were deemed to be undergoing neoplastic change. Vacuolization and intercellular spacing were observed only occasionally in the basal layer of the epithelium undergoing neoplastic change, although in the more superficial layers of this epithelium, these two features were more frequently observed. In the areas of epithelium which exhibited frank neoplastic change deep in the connective tissue wall of the cyst, vacuolization and intercellular spacing of the basal cells were more commonly observed. This was not invariably so, however, and the histologic.appearance differed in various areas of the same lesion. Vickers and Gorlin15 also describe a homogenization or hyalinization of a uniform, thin, bandlike area of the fibrous connective tissue adjacent to the epithelium in six of their ten cases. In the present sample, this change in the connective tissue was observed adjacent to the frankly neoplastic epithelium which was deep within the wall of the cyst. However, this change was not a constant finding and, along with vacuolization and intercellular spacing of the basal cells, could not be used as a criterion for the development of neoplasia in the epithelium which lined the cyst cavity. Although the epithelium lining the cyst cavity was always continuous with that forming the ameloblastoma, the possibility that the neoplasm arose from odontogenic epithelium known to be present in the
496
McMillan
and Smillie
Fig. 11. Case 5. Photomicrograph
Oral S#urg. May, 11981
of cyst wall showing
ameloblastomatousepithelium (E). (Hematoxylin and
phloxine stain. Magnification, x 1IO.) connective tissue of the walls of sqme dentigerous Cyst&l6 with subsequent fusion to the epithelium lining the cyst, cannot be ruled out. The lesions recorded in the present article (Cases 1 to 5) were treated 2, 4, 13, 1, and 7 years ago, respectively, and to this date none has recurred. Although the series is small and in a number of the cases the time s&n is short, this lack of recurrence perhaps supports the observations that ameloblastomas associated with dentigerous cysts represent a much less aggressive variety of the neoplasm and that their rate of.recurrence is distinctly lower than that of the multicystic and solid variants. l7
10. 11. 12. 13.
The practitioners who supplied the clinical material are thanked, as are Miss N. Taylor and her staff who prepared the histologic material. REFERENCES
1. Cahn, L. R.: The DentigerousCyst Is a PotentialAdamantinoma,Dent. Cosmos. 75: 889-893,1933. 2. Sonesson,A.: OdontogenicCystsand Cystic Tumours of the Jaws; Roentgen-diagnostic and Patho-anatomic Study, Acta Radiol. (Suppl.) 81: I-159, 1950. 3. Bemier, J. L., and Tiecke, R. W.: A Compilation of the Material Received by the Registry of Oral Pathology, J. Oral Surg. 9: 341-348, 1951. 4. Stanley, H. R., and Diehl, D. L.: Ameloblastoma Potential of Follicular Cysts, ORAL SURG. 20: 260-268, 1965. 5. Meyer, I.: Comments on an Article by Getter, L., 1. Oral Surg. 23:‘253, 1965.
14. 15. 16. 17.
Lucas, R. B.: Pathology of Tumours of the Oral Tissues. ed. 3, London, 1976, Churchill Livingstone, chaps. 3 and 31. Small. I. A., and Waldron, C. A.: Ameloblastomas of the Jaws, ORAL SURG. 8: 281-297, 1955. Hutton, C. E.: Occurrence of Ameloblasloma Within a Dentigerqus Cyst, ORAL SURG. 24: 147-150, 1967. Dresser, W. J., and Segal, E.: Ameloblastoma Associated With a Dentigerous Cyst in a 6-Year-Old Child, ORAL SURG. 24: 388-391, 1967. Quinn, J. H., and Foumet, L. F.: Dentigerous Cyst With Mural Ameloblastoma: Report of Case, J. Oral Surg. 27: 662-664, 1969. Taylor, R. N.: Dentigerous Cyst With Ameloblastomatous Proliferation: Report of Case, J. Oral Surg. 29: 136-140, 1971. Struthers, P., and Shear, M.: Root Resorption by Ameloblastomas and Cysts of the Jaws, Int. J. Oral Surg. 5: 128-132, 1976. Shafer, W. G., Hine, M. K., and Levy. B. M.: A Textbook of Oral Pathology, ed. 3, Philadelphia, 1974, W. B. Saunders Company, chap. 4. Kramer, I. R. H.: Ameloblastoma: A Clinicopathological Appraisal, Br. J. Oral Surg. 1: 13-28, 1963. Vickers, R. A., and Gorlin, R. J.: Ameloblastoma: Delineation of Early Histoparhologic Features of Neoplasia, Cancer 26: 699-7 10, 1970. Gorlin, R. J.: Potentialities of Oral Epithelium Manifest by Mandibular Dentigemus Cysts, ORAL SURG. 10: 271-284, 1957. Robinson, L., and Martinez, M. G.: Unicystic Ameloblastoma: A Prognostic Distinct Entity. Cancer 40: 2278-2285, 1977.
Reprint requests
to.
Dr. M. D. McMiUan Department of Oral Biology School of Dentistry, University of Otago P. 0. Box 647 Dunedin, New Zealand
E. TOMICH,
D.D.S., M.S.D.
American Academy of Oral Pathology Indiana Universi~ School of Dentist0 l/2/ West Michigan Street Indianapolis, Indiana 46302
Short communications & case reports Ameloblastomas associated with dentigerous cysts M. D. McMillan. DEPARTMENT
M.D.S., Ph.D. I and A. C. Smillie, M.D.S., Ph.D., Dunedin, New Zealand
OF ORAL
BIOLOGY,
SCHOOL
OF DENTISTRY,
UNIVERSITY
Five cases of ameloblastoma apparently arising in the walls of dentigerous Evidence supporting this concept is discussed.
T
he apparent development of ameloblastoma in the wall of a dentigerous cyst was first described by Cahn’ in 1933. Since that time, many such casks have been recorded. Sonesson,2 in reporting thirty-nine cases of ameloblastoma, considered that at least ten of these had arisen from odontogenic cysts, while Bemier and Tiecke3 state that approximately 33 Percent of the eighty-eight ameloblastomas in their series arose in follicular cysts (dentigerous cysts). In 1965, Stanley and Diehl” reviewed the English-language publications and found 446 cases of ameloblastoma. They added 193 cases from the Armed Forces Institute of Pathology and two cases from the National Institutes of Health, making a total of 641 cases. Of these 641 cases, 108 were said to be definitely associated with an impacted tooth .and/or a follicular cyst (dentigerous cyst). Meyer,j in comments on a reported case of an ameloblastoma arising in the wall of a dentigerous cyst, stated that in a 25year Period at the Tufts University School of Dental Medicjne, twenty-five ameloblastomas had been diagnosed. Over the same perioq, 500 dentigerous cysts were examined and, of these, only four showed ameloblastomatous changes in their walls. In spite of the large number of reports of ameloblastic change in the walls of dentigerous cysts, Lucas’
0030-4220/81/050489+08500.80/0
@
1981
‘he C. V. Mosby Co.
OF OTAGO
cysts are presented.
points out that the evidence is somewhat equivocal, as in many of the reports no definite evidence is offered to show that a neoplasm has developed from what was previously a simple cyst. The purpose of this study is to present five cases in which an ameloblastoma appears to be arising in the wall of a dentigerous cyst and to draw attention to data supporting this possibility. CASE 1
A 21-year-old man presentedwith a swelling of the left side of the face. Radiographic examination revealed a large, well-defined, unilocular radiolucency associatedwith an unerupted third molar. Gross examination failed to reveal any obvious mural thickening. Histologically, the cyst cavity was lined in part with degenerate stratified squamous epithelium infiltrated with inflammatory cells (Fig. 1). Elsewhere, the cyst cavity was not lined with epithelium. The bulk of the cyst wall consisted of a relatively acellular, dense, fibrous connective tissue. In someplaces, the epithelial lining liad a more odontogenic appearance.Islands of odontogenic-appearing epithelium were found in the adjacent connective tissue. These epithelial @landsconsistedof a peripheral layer of cuboidal to low-columnar cells which surroundedmore stellate cells and frequently showed cystic degeneration(Fig. 2). 489
490
MrMillan
and Smillie
Oral Surg. May, 1981
Fig. 1. Case 1. Photomicrograph of the thin epithelial lining (arrows) and inflamed connective tissue (A) forming the cyst wall. (Hematoxylin and phloxine stain. Magnification, x220.)
Fig. 2. Case 1. Photomicrograph of cyst wall showing ameloblastomatous epithelial islands composed of a peripheral layer of cuboidal or columnar cells (arrows) surrounding more stellate cells (S) Note areas of cystic degeneration (arrou+zeads). (Hematoxylin and phloxine stain. Magnification, x 110.)
Volume 5 1 Number 5
Ameloblastomas associated lcith dentigerous c,ysts 497
Fig. 3. Case 2. Radiograph showing well-defined unilocular
Fig. 4. Case 2. Radiograph of fixed pathology specimen show-
radiolucency (RJ involving the ramus and body of the left mandible. Note root resorption (arrow).
ing cyst cavity (C), two mural thickenings (M), and root resorption (nrro\~)
CASE 2
the soft-tissue projection, the epithelial lining had a more odontogenic appearance (Fig. 7). This odontogenic epithelium was continuous with sheets and strands of similarappearing epithelium present within the soft-tissue projection and extending deeply into the connective tissue of the cyst wall. Cystic areas were found within both the epithelial sheets and the connective tissue. However. the epithelium lining these small cysts was ameloblastomatous in appearance, with cuboidal or columnar basal cells, thus contrasting sharply with the stratified squamous epithelium which lined the large cyst cavity.
A 12-year-old boy presented with a swelling of the left side of the mandible. Radiographic examination revealed a well-demarcated unilocular radiolucency associated with an unerupted second molar (Fig. 3). The roots of the first permanent molar, which were also associated with the radiolucency, showed obvious resorption. Radiographic and gross examination of the specimen revealed that the crown of the second molar appeared to be in the cyst cavity (Fig. 4). Two mural outgrowths extended into the cyst cavity. Histologic examination of the area which contained the second molar revealed that the reduced enamel epithelium was continuous with, and formed part of, the epithelial lining of the cyst cavity (Fig. 5). This epithelium was, in the main, only two to three cells thick and there was no evidence of keratinization. In the areas of the two gross mural thickenings, proliferation of epithelium and of a delicate connective tissue was found. This epithelium was continuous with that lining the cyst, and it consisted of sheets and strands of cells that had an odontogenic appearance (Fig. 6). Histologic examination of the first molar confirmed that resorption of the roots had occurred. CASE 3
A 15year-old girl presented with an acute painful swelling that had developed in the left mandibular molar region 4 weeks previously. Radiographic examination revealed a large, well-defined, unilocular radiolucency associated with an unerupted second molar. The roots of the erupted first molar were also associated with the radiolucency and showed resorption. Grossly, a solid mass of tissue was found extending between the crown of the second molar and the wall of the cyst to which it was attached. Histologically, the cyst wall consisted of a thin, stratified, squamous epithelium with a thick backing of dense fibrous connective tissue. In many areas, a moderate infiltration of lymphocytes and plasma cells was present in the connective tissue immediately beneath the epithelium. In the vicinity of
CASE 4
A 14-year-old boy presented with a painful swelling on the left side of the face. Radiographic examination revealed a unilocular, well-circumscribed radiolucency associated with unerupted second and third molars. Both the erupted first molar and second premolar showed evidence of root resorption. Histologically, the wall of the cyst consisted of stratified squamous epithelium which, in places, showed hyperplasia with elongation of the rete pegs, supported by a thick and cellular connective tissue. There was a moderate infiltration of lymphocytes and plasma cells adjacent to much of this epithelium (Fig. 8). In one area the epithelium had a more odontogenic appearance, and in the associated connective tissue there were many epithelial islands and cords, some of which showed cystic degeneration (Fig. 9). The reduced enamel epithelium was continuous with the epithelium which lined the cyst. CASE 5
A 12-year-old boy presented with an asymptomatic right facial swelling. Radiographic examination revealed a large, well-circumscribed, unilocular radiolucency associated with an unerupted third molar. The roots of the involved first molar showed resorption. Six days prior to operation, an episode of acute inflammation occurred. Histologically, the bulk of the cyst cavity was lined with a
492
McMillan
and Smillie
Oral Surg. May. 19sl
Fig. 5. Case 2. Photomicrograph through a section which includes the unerupted second molar(T) . Note reduced enamel epithelium (arrows). which was continuous with the cyst lining, and enamel space (E). (Hematoxylin and phloxine stain. Magnification, X40.)
Fig. 6. Case 2. Photomicrograph in area of the smaller mural thickening showing cyst cavity (Cj; thin epithelium lining cyst (arrows); strands and sheets of ameioblastomatous epithelium (arrowheads). (Hematoxylin and phloxine stain. Magnification, x40.)
Volume 5 I Number 5
Ameloblastomas
associated
with dentigerous
cysts
Fig. 7. Case 3. Photomicrograph through cyst cavity (C) showing the lining of stratified squamous epithelium (arron~s) and area of ameloblastomatous epithelium (A). (Hematoxylin and phloxine stain. Magnification, X 40.)
Fig. 8. Case 4. Photomicrograph of the wall of the cyst showing stratified squamous epithelium (arrows) and inflame’d connective tissue (C). (Hematoxylin and phloxine stain. Magnification, x ZOO.)
493
494
McMillan
and Smillie
Oral Surg. blay, 1981
Fig. 9. Case 4. Photomicrograph showing ameloblastomatous epithelium (E) in the wall of the cyst. (Hematoxylin and phloxine stain. Magnification, x40.)
stratified squamous epithelium which was supported by a thick layer of dense connective tissue (Fig. 10). In places, the epithelial lining was absent. A mixed inflammatory cell infiltration was found throughout most of the connective tissue of the cyst wall. In places, the epithelial lining was more odontogenic in appearance and marked proliferation of the epithelium into the underlying connective tissue was found. These deeper epithelial elements consisted of cords and islands of ameloblastomatous-appearing epithelium (Fig. 11).
DISCUSSION All the lesions were diagnosed initially as dentigerous cysts on the basis of their radiographic appearances. This emphasizes the necessity of submitting all dentigerous cysts for histopathologic examination. In a review of 1,036 cases of ameloblastoma, Small and Waldron’ report that the average age of patients seeking treatment was 38.9 years, while the average age at which symptoms from the lesion were first noted was 32.7 years. All the lesions in the present study were from considerably younger patients. Stanley and Diehl,4 from a study of 108 cases of ameloblastomas associated with demigerous cysts and/or impacted teeth, report that the average age at diagnosis was 21 years. This is 18 years earlier than that for the diagnosis of all types of ameloblastomas.7 Since the review by Stanley and Diehl,’ only a small number of reports of
ameloblastomas associated with dentigerous cysts have appeared in the literature. A critical evaluation of these reports shows that the great majority of the patients were in the 6 to 14-year age group.*-” Dentigerous cysts themselves are generally detected in children or adolescents .6 The considerably earlier age for the clinical presentation of ameloblastomas associated with dentigerous cysts as opposed to ameloblastomas in general offers support for the concept that ameloblastomas can arise in the walls of dentigerous cysts. This is contrary to the suggestion that such lesions are ameloblastomas which have undergone cystic degeneration, with the coalescence of numerous small cysts to form one large one. If the latter process took place, it would be reasonable to suggest that such lesions would be found in the age group that includes ameloblastomas in general and not in a younger group. Small and Waldron7 have stated that all ameloblastomas begin as solid tumors and gradually become more cystic with age. This could well apply to ameloblastomas arising from dentigerous cysts. The present findings support this, as cyst formation was present in all five ameloblastomas reported here. In our experience, the stroma of uncomplicated ameloblastomas is not infiltrated by inflammatory cells.
Volume 5 I Number 5
Atneloblastot~asassociated with detttigerous qsts
495
Flg. 10. Case 5. Photomicrograph of cyst wall showing stratified squamous epithelium (E) and inflamed connective tissue (CJ. (Hematoxylin and phloxine stain. Magnification, x 220.)
whereas that of dentigerous cysts often is. This experience would appear to be shared by others.“, I3 In all cases described in the present report, varying numbers of inflammatory cells were found in the wall of the cyst. This can be interpreted as evidence that the major cystic lesion is a dentigerous cyst. The findings in Cases 2 and 4 that the reduced enamel epithelium which surrounded the crown of the impacted tooth was continuous with that lining the large cyst cavity is further evidence that these lesions were initially dentigerous cysts. Because of the nature of the material submitted for histologic examination in the other three cases, this aspect of these lesions, unfortunately, could not be evaluated. In each of the cases presented in this report, the epithelium lining the large cyst changed from a stratified squamous epithelium to one having a markedly odontogenic appearance in the region of the ameloblastomatous tissue. The lining epithelium was always continuous with that forming the ameloblastoma, irrespective of whether the ameloblastoma was found in the cyst wall proper or as a projection into the cyst lumen. This finding supports the suggestion that the arneloblastoma arose by transformation of the epithelial lining of the cyst.14 Following a histologic study of 10 jaw cysts and an analysis of the literature, Vickers and Gorlin” concluded that cysts which showed areas of epithelium with hyperchromatism of basal cell nuclei, palisading with polarization of the basal cells, and cytoplasmic vacuolization of (especially) basal cells with intercellu-
lar spacing were associated with ameloblastoma in a high percentage of cases. All the examples in the present report exhibited hyperchromatism of basal cell nuclei and palisading with polarization of the basal cells in areas of cyst lining which were deemed to be undergoing neoplastic change. Vacuolization and intercellular spacing were observed only occasionally in the basal layer of the epithelium undergoing neoplastic change, although in the more superficial layers of this epithelium, these two features were more frequently observed. In the areas of epithelium which exhibited frank neoplastic change deep in the connective tissue wall of the cyst, vacuolization and intercellular spacing of the basal cells were more commonly observed. This was not invariably so, however, and the histologic.appearance differed in various areas of the same lesion. Vickers and Gorlin15 also describe a homogenization or hyalinization of a uniform, thin, bandlike area of the fibrous connective tissue adjacent to the epithelium in six of their ten cases. In the present sample, this change in the connective tissue was observed adjacent to the frankly neoplastic epithelium which was deep within the wall of the cyst. However, this change was not a constant finding and, along with vacuolization and intercellular spacing of the basal cells, could not be used as a criterion for the development of neoplasia in the epithelium which lined the cyst cavity. Although the epithelium lining the cyst cavity was always continuous with that forming the ameloblastoma, the possibility that the neoplasm arose from odontogenic epithelium known to be present in the
496
McMillan
and Smillie
Fig. 11. Case 5. Photomicrograph
Oral S#urg. May, 11981
of cyst wall showing
ameloblastomatousepithelium (E). (Hematoxylin and
phloxine stain. Magnification, x 1IO.) connective tissue of the walls of sqme dentigerous Cyst&l6 with subsequent fusion to the epithelium lining the cyst, cannot be ruled out. The lesions recorded in the present article (Cases 1 to 5) were treated 2, 4, 13, 1, and 7 years ago, respectively, and to this date none has recurred. Although the series is small and in a number of the cases the time s&n is short, this lack of recurrence perhaps supports the observations that ameloblastomas associated with dentigerous cysts represent a much less aggressive variety of the neoplasm and that their rate of.recurrence is distinctly lower than that of the multicystic and solid variants. l7
10. 11. 12. 13.
The practitioners who supplied the clinical material are thanked, as are Miss N. Taylor and her staff who prepared the histologic material. REFERENCES
1. Cahn, L. R.: The DentigerousCyst Is a PotentialAdamantinoma,Dent. Cosmos. 75: 889-893,1933. 2. Sonesson,A.: OdontogenicCystsand Cystic Tumours of the Jaws; Roentgen-diagnostic and Patho-anatomic Study, Acta Radiol. (Suppl.) 81: I-159, 1950. 3. Bemier, J. L., and Tiecke, R. W.: A Compilation of the Material Received by the Registry of Oral Pathology, J. Oral Surg. 9: 341-348, 1951. 4. Stanley, H. R., and Diehl, D. L.: Ameloblastoma Potential of Follicular Cysts, ORAL SURG. 20: 260-268, 1965. 5. Meyer, I.: Comments on an Article by Getter, L., 1. Oral Surg. 23:‘253, 1965.
14. 15. 16. 17.
Lucas, R. B.: Pathology of Tumours of the Oral Tissues. ed. 3, London, 1976, Churchill Livingstone, chaps. 3 and 31. Small. I. A., and Waldron, C. A.: Ameloblastomas of the Jaws, ORAL SURG. 8: 281-297, 1955. Hutton, C. E.: Occurrence of Ameloblasloma Within a Dentigerqus Cyst, ORAL SURG. 24: 147-150, 1967. Dresser, W. J., and Segal, E.: Ameloblastoma Associated With a Dentigerous Cyst in a 6-Year-Old Child, ORAL SURG. 24: 388-391, 1967. Quinn, J. H., and Foumet, L. F.: Dentigerous Cyst With Mural Ameloblastoma: Report of Case, J. Oral Surg. 27: 662-664, 1969. Taylor, R. N.: Dentigerous Cyst With Ameloblastomatous Proliferation: Report of Case, J. Oral Surg. 29: 136-140, 1971. Struthers, P., and Shear, M.: Root Resorption by Ameloblastomas and Cysts of the Jaws, Int. J. Oral Surg. 5: 128-132, 1976. Shafer, W. G., Hine, M. K., and Levy. B. M.: A Textbook of Oral Pathology, ed. 3, Philadelphia, 1974, W. B. Saunders Company, chap. 4. Kramer, I. R. H.: Ameloblastoma: A Clinicopathological Appraisal, Br. J. Oral Surg. 1: 13-28, 1963. Vickers, R. A., and Gorlin, R. J.: Ameloblastoma: Delineation of Early Histoparhologic Features of Neoplasia, Cancer 26: 699-7 10, 1970. Gorlin, R. J.: Potentialities of Oral Epithelium Manifest by Mandibular Dentigemus Cysts, ORAL SURG. 10: 271-284, 1957. Robinson, L., and Martinez, M. G.: Unicystic Ameloblastoma: A Prognostic Distinct Entity. Cancer 40: 2278-2285, 1977.
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Dr. M. D. McMiUan Department of Oral Biology School of Dentistry, University of Otago P. 0. Box 647 Dunedin, New Zealand