- Email: [email protected]
Relative incidence of odontogenic tumors and oral and jaw cysts in a Canadian population
Relative incidence of odontogenic tumors and oral and jaw cysts in a Canadian population Tom D. Daley, DDS, MSc, FRCDCa George P. Wysocki, DDS, PhD,b and Gordon A. Pringle, DDS, PhD, FRCDC,” London, Ontario, Canada UNIVERSITY
OF WESTERN
ONTARIO
The diagnoses of 40,000 consecutively accessioned oral biopsies from the Oral Pathology Diagnostic Service, University of Western Ontario, London, Canada, were reviewed. All odontogenic neoplasms, neoplasm-like lesions (tumors), and true cysts of the oral tissues and jaws were listed. Clinical data were reviewed, and microscopic diagnoses were confirmed for cases in which diagnoses were ambiguous. Records of all caseswere examined to identify distant referrals that were not representative of the study population. Of a total of 445 (1.11%) odontogenic tumors, 392 (0.98%) were lesions from patients in the usual local drawing area of the biopsy service; 53 were referred from distant centers. From the local population, odontomas were by far the most common tumor (51.53%) followed by ameloblastomas (13.52%) and peripheral odontogenic fibromas (8.93%). Locally, radicular (periapical) cysts were the most common odontogenic cyst (65.15%) followed by the dentigerous cyst (24.08%) and the odontogenic keratocyst (4.88%). The most common nonodontogenic cyst was the nasopalatine duct cyst that accounted for 73.43% of this subset of cysts. Surprisingly few studies of this type are available, especially for odontogenic tumors. These data are important to assess geographic differences in the incidence of lesions and to allow clinicians to make realistic judgments in counseling patients before biopsy about the probability of diagnosis and risks associated with nonspecific clinical or radiographic lesions. (ORAL SURC ORAL MED ORAL PATHOI. l!I94;77:276-80)
Records concerning the incidence of most types of neoplasmsare carefully kept by government or health care agenciesin most countries. l-3Thesedata are used to assessthe relative importance of various neoplasms to the well-being of the population and to assessgeographic differences that may lead to clues concerning the causesof these lesions. For example, a disproportionate number of oral squamous cell carcinomas have been found in parts of India, and attempts have been made to relate these data to specific population habits such as betel nut chewing.4,5 However, there is little information on the relative incidence of odontogenie tumors and little more on the incidence of oral and jaw cysts. The records of oral pathology diagnostic servicesare excellent sourcesof such information, despite the inevitable biases that are present in such studies. Nevertheless, information gained from these files is valuable, and probably represents the only large source of such data presently available. The purpose of this study was to determine the incidence of odontogenic tumors, odontogenic cysts, and nonodontogenic cysts of the oral region, relative to all lesions in the biopsy service and relative to one another, and to compare these data with previously published reports from other geographic areas. “Division of Oral Pathology, Department of Pathology. bProfessor and Chairman, Division of Oral Pathology, Department of Pathology. Copyright @ 1994 by Mosby-Year Book, Inc. 0030-4220/94/$3.00 + 0 l/14/52902
276
In this article, the term tumor is used in its generic senseand includes odontogenic neoplasmssuch as the ameloblastoma, hamartomas such as the odontoma, and lesions of uncertain histogenesis such as the peripheral odontogenic fibroma. MATERIAL AND METHODS
The diagnosesof 40,000 consecutively accessioned oral biopsies from the files of the Oral Pathology Diagnostic Service, University of Western Ontario, London, Canada, from 1967 to 1993 were reviewed. AI1 casesof odontogenic tumors, odontogenic cysts, and nonodontogenic cysts were listed. Clinical data and microscopic diagnosesof all casesfor which there was any doubt about the listed diagnoses were reviewed. Most casesbefore 1976 were reviewed to update diagnosesthat resulted from the advancement of knowledge and the definition of new entities. Records from all caseswere reviewed with respect to the contributor of the tissues. All distant referral caseswere separated from casescontributed by clinicians within the local geographic area of the biopsy service that consisted largely of southern Ontario. Odontogenic tumors as described by Regezi and Sciubba,6 the calcifying odontogenic cyst as described by Praetorius et a1.,7peripheral odontogenic fibroma as described by Gardner,8 and primary intraosseous carcinoma as described by Elzay9 were studied. The enameloma as described by Shafer et al. lo was not included because it was considered to be a developmental anomaly. Florid osseousdysplasia as described by Melrose et
Daley. Wysocki, and Pringle
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 77, Number 3 Table
277
I. Odontogenic tumors in 40,000 consecutively accessionedoral biopsies Lesion
Local
Ameloblastoma Calcifying epithelial odontogenic tumor Adenomatoid odontogenic tumor Calcifying odontogenic cyst Squamous odontogenic tumor Clear cell odontogenic tumor Odontogenic carcinoma Odontogenic tumor NOS Central odontogenic fibroma Peripheral odontogenic fibroma Odontogenic myxoma Cementoblastoma Odontogenic sarcoma Ameloblastic ftbroma Ameloblastic tibro-odontoma Odontoma-compound -complex Odontoameloblastoma Dentinoma Ameloblastic fibro-sarcoma TOTAL
53 5 13 18 0 0 1 1 19 35 20 I 0 6 12 128 74 0 0 0 5-2 (0.98%)
Total
Percentage of odontogenic tumors (local only)
19 8 14 18 I 0 I 1 25 36 24 7 0 7 14 130 74 0 0 - 0 445 (1.11%)
13.52 1.28 3.32 4.59 0.00 0.00 0.26 0.26 4.85 8.93 5.10 1.79 0.00 1.53 3.06 32.65 18.88 0.00 0.00 0.00 100.02%
Referrals 26 3 1 0 1 0 6 0 6 1 4 0 0 1 2 2 0 0 0 0 53
NOS = not otherwise specified
al.” and considered to be synonymous with such terms as gigantiform cementoma was not included becauseit was considered to be a nonodontogenic lesion of bone. A similar argument could be made for six casesof periapical cemental dysplasia that were subsequently deleted. Similarly, some pathologists regard the central cementifying fibroma to be a variant of central ossifying fibroma; therefore 50 such caseswere not included in this study. No attempt was made to separate central from peripheral lesions except for the odontogenic fibroma or to separate ameloblastomasinto clinical or histologic types. Combined epithelial odontogenic tumors as described by Damm et a1.t2were classified according to the predominant histologic pattern as calcifying epithelial odontogenic tumor or adenomatoid odontogenic tumor. The simple and World Health Organization types of central odontogenic fibroma were combined. Also studied were cysts as described by Shear,13the glandular odontogenic cyst as described by Gardner et a1.,14the paradental cyst as described by Craig,15 the true sebaceouscyst and the steatocystomasimplex as described by Daley,16 and the heterotopic gastrointestinal cyst as described by Daley et a1.17All globulomaxillary cysts were reviewed and reclassified as described by Wysocki. ‘* Residual radicular cysts were included with radicular cysts. Eruption cysts were separated from dentigerous cysts. Aneurysmal bone cysts and traumatic bone cysts were not included
because they are pseudocyststhat fail to satisfy the definition of a cyst. RESULTS
Tables I, II, and III list the results of this study. DISCUSSION
Despite the obvious need to know the incidence and relative frequency of odontogenic tumors, there are surprisingly few such studies.19M23 In somestudies, the scopeof tumors listed is so limited that a full comparison is impossible.24-27In addition, some of the studies are too old to draw valid comparisons becauseof the definition of new entities and the change in interpretation of other entities.21 There are more studies that addressthe relative frequency of odontogenic and jaw cysts13$ 21,28-33but none from a Canadian population. Again many of these studies are outdated, limited, and not appropriate for comparison.21p32,33 Data from a diagnostic biopsy service are biased in several respects. The relative number of specimens will vary somewhat with the practice of the contributors. A service that receives tissues primarily from endodontists will have a disproportionate number of periapical lesions whereasservicesthat receive tissues primarily from periodontists will seea disproportionate number of gingival lesions. Our biopsy service receives most of its tissues from general dental practioners and oral surgeons. Endodontists, periodon-
278
Daley,
Wysocki,
and Pringle
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY March
I994
II. Odontogenic cysts in 40,000 consecutively accessionedoral biopsies -~--~-~~-7------~-... ~
Table
Lesion
Local
Radicular cyst Dentigerous cyst* Eruption cyst Lateral periodontal cyst Adult gingival cyst Odontogenic keratocyst Cyst of undetermined origin Paradental cyst Glandular odontogenic cyst TOTAL
4461 1649 40 101 33 334 193 33 3 6,847 (17.12%)
Rejzrrals
Total ----.--
_I---.
4468 1662 40 106 33 335 196 33 6 6879 (17.20%)
7
13 0 5 0 I 3 0 3 32
Percentage of odontogmic, cr~tr ilocal onlvj 65.15 24.08 0.58 1.48 0.48 4.88 2.82 0.48 0.04
*see text.
Table
III. Nonodontogenic oral and jaw cysts in 40,000 consecutively accessionedoral biopsies Lesion
Nasopalaline duct cysts Nasolabial cyst Cyst of undetermining origin Median mandibular cyst Benign lympboepithelial cyst Dermoid cyst Epidermoid cyst True sebaceous cyst Steatocystoma simplex Heterotopic gastrointestinal cyst Surgical ciliated cyst Thyroglossal duct cyst TOTAL
Local
Referrals
293 7 1 1 65 1 21 3 1 0 6 0 399 (I .OO%)
tists, oral pathologists, prosthodontists, and medical practitioners also contribute. We believe that a reasonable cross section of tissues is received in our biopsy service, resulting in a reasonably valid relative incidence of lesions. A second source of bias arises from lesions that are diagnosed clinically and radiographically but are not biopsied. For example, our archives contained few casesof periapical cemental dysplasia in part becauseof a justified reluctance to biopsy this condition. A third source of bias results from the inclusion of referrals from distant contributors. These referrals can significantly skew the results becausethey are not representative of the study population. Centers of expertise are likely to have larger numbers of interesting, rare, or diagnostically difficult casesreferred to them. Odontogenic tumors and cysts are commonly referred to oral pathologists by general pathologists. For example, in this study, six of the sevenodontogenic carcinomas were from distant referrals, and 11.91%of all odontogenic tumors studied were from distant centers. To reduce this bias, the geographic location of contributors was determined,
2 0 0 0 1 0 0 0 0 0 0 1 4
Total 295 I 1 1 66 1 21 3 1 0 6 1 403 (1.01%)
Percentage of nonodontogenic cysts (local) 13.43 1.75 0.25 0.25 16.29 0.25 5.26 0.75 0.25 0.00 1.50 0.00
and distant referrals were excluded from percentage calculations (Tables I, II, and III), Additional bias can result from the omission of lesions referred to hospital-based pathology laboratories within the geographic area of the study population. Despite these biases that were corrected whenever possible, we believe that our data is reasonably representative and offers a valid contribution to our knowledge of the relative incidence of these lesions. Regezi et a1.19published a similar study from Michigan, that involved 706 odontogenic tumors derived from 54,534 biopsy specimens, although they did not correct for distant referrals. They found that odontogenic tumors accounted for 1.3%of their biopsies,which is similar to our finding of 1.11%when we include referrals in our series. Local casesaccounted for 0.98% of the 40,000 cases.Table IV lists comparisons in the relative percentages of odontogenic tumors from selected studies. Our sample was also similar to that of Regezi et all9 with regard to reiative incidence of individual odoatogenic tumors. The only notable difference was our incidence of 8.93% for
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 77, Number 3 Table IV.
Daley, Wysocki, and Pringle
279
Comparison of the relative percentage of odontogenic tumors from selected references and this
study Present study
Ameloblastoma Calcifying epithelial odontogenic tumor Adenomatoid odontogenic tumor Calcifying odontogenic cyst Central odontogenic fibroma Peripheral odontogenic fibroma Odontogenic myxoma Periapical cemental dysplasia Ameloblastic fibroma Ameloblastic fibro-odontogenic Odontoma-compound -complex *Combined
Ontario
Regezi et a1.t9 U.S.A.
Gunham et aLzo Turkey
13.52 1.28 3.32 4.59 4.85 8.93 5.10 1.53 3.06 32.65 18.88
11
36.5 1.5 2.5 1.0 4.5 12.5 4.5 1.0 9.0 9.0
Wu and Chan23 Hong Kong 62.19 3.66 2.44 3.66 1.22
2.44 1.22 6.10*
total for complex and compound odontomas.
the peripheral odontogenic fibroma, which was not well defined at the time of their article.” They found a higher relative incidence of odontomas; however, in both studies and in the study by Thompson27in Oregon, odontomas were by far the most common odontogenic tumor. The overall similarity in the incidence of odontogenic tumors may be a reflection of the close geographic proximity of Michigan and Ontario. The study by Gunham et a1.20from Turkey and by Wu and ChanZ3in Hong Kong showed a remarkable geographic variation from our study. The incidences of ameloblastoma were approximately three and six times higher, respectively. Conversely, their incidences of odontomas were approximately five and eight times lower, respectively, than the Ontario study. Whether these differences reflect real geographic variations or are a result of bias is unclear. Nevertheless, the possibility of real geographic variations should be considered, especially in light of the apparently high relative incidence of ameloblastomas in Africa.22l 24,26 Bhaskar’s study21 is outdated and supplies only limited information, although it is still being quoted.20,33,34Understandably, many of the newer entities were not included. In addition, relative percentageswere skewed by the interpretation of hyperplastic dental follicles as central odontgenic fibromas.35 The incidence of odontogenic cysts in this study was similar to that of other studies. These cysts as a group comprised 17.12% of the 40,000 biopsies. The proportion of 65.15% for radicular cysts lies within the range of 52.3% reported by Shear13(although he included nonodontogenic cysts and pseudocysts) and the 77.7% reported by Main.28 Interestingly, Cawson and Eveson arrived at the same 65% figure by combining information from several large seriesin the lit-
erature. Dentigerous cysts were the second most common odontogenic cyst in our series (24.08%) somewhat more than that of Sheari (16.6%), Killey and Kay29(16.2%), and Radden and Reade3’ (17.4%). This difference may reflect the difficulty in diagnosing small dentigerous cysts becauseprecise histologic criteria are not available, and the diagnosis rests largely in the opinion of the operating surgeon. Histologic diagnosis alone is impossible.37A large variation in the relative incidence of odontogenic keratocysts exists between various studies. We found an incidence of 4.88% that contrasts with the findings of Shear13(11.2%) and of Radden and Reade3’ (17.4%). Interestingly, the mean found by Cawson and Eveson36was 7%, which is closer to our findings. The glandular odontogenic cyst is a newly described entity. l4 Our study revealed three local cases and three referred cases,making this cyst a rare lesion relative to other odontogenic cysts. As the lesion becomesmore widely recognized and gains widespread acceptance, its relative incidence may increase. Nonodontogenic cystscomprised 1.O%of the 40,000 biopsies. In agreement with other studies,13T 28,3othe nasopalatine duct cyst was by far the most common and accounted for 73.43% of our cases,whereas the benign lymphoepithelial cyst accounted for 16.29% and epidermoid cysts 5.26%. Other cysts were uncommon. The existence of the globulomaxillary cyst is doubtful.‘*> 38,39 Distant referrals to centers of expertise reflect difficulties in interpretating uncommon or rare lesions. We found most referrals to be in the odontogenic tumor group (11.9 1%) with a high proportion of ameloblastomas and odontogenic carcinomas. Referrals of cysts, on the other hand, represented less than 1% in both the odontogenic and nonodontogenic groups.
280
Daley, Wysocki, and Pringle
However, a large proportion of glandular odontogenic cysts were referrals (50%) whereas the most commonly referred cyst was the dentigerous cyst (13 of 1662 cases). REFERENCES 1. Waterhouse J, Muir C, Correa P, Porvell J, Davis W, eds. Cancer incidence in five continents, ~013. Lyon, France: World Health Organization, 1976. 2. Gaudette LA, Makomaski Illing EM, eds. Canadian cancer statistics 1992. Toronto: National Cancer Institute of Canada, 1992. 3. Riggan WB, VanBruggen J, Acquavella JF, Beaubier J, Mason TJ. U.S. cancer mortality rates and trends, 1950-1979, vol 3. Bethesda, Maryland: National Cancer Institute/Environmental Epidemiology Branch, 1983. 4. Pindborg JJ, Chawla TN, Misra RK, Nagpaul RK, Gupta VK. Frequency of oral cancer, leukoplakia, leukokeratosis, leukoedema, submucous fibrosis, and lichen planus in 10000 Indians in Lucknow, Uttar Pradesh, India: preliminary report. J Dent Res 1965;44:615. 5. Pindborg JJ, Kiaer J, Gupta PC, Chawla TN. Studies in oral leukoplakias: prevalence of leukoplakia among 10000 persons in Lucknow, India, with special reference to use of tobacco and betel nut. Bull World Health Organ 1967;37:109-16. 6. Regezi JA, Sciubba JJ. Oral pathology: clinical-pathologic correlations, 2nd ed. Philadelphia: WB Saunders, 1993:36291. 1. Praetorius F, Horting-Hansen E, Gorlin RJ, Vickers RA. Calcifying odontogenic cyst: range, variations, and neoplastic potential. Acta Odontol Stand 1981;39:227-40. 8. Gardner DG. The peripheral odontogenic fibroma: an attempt at clarification. ORAL SURG ORAL MED ORAL PATHOL 1982;54:40-8. 9. Elzay RP. Primary intraosseous carcinoma of the jaws: review and update of odontogenic carcinomas. ORAL SURC ORAL MED ORAL PATHOL 1982;54:299-303. 10. Shafer WG, Hine MK, Levy BM. A textbook of oral pathology, 4th ed. Philadelphia: WB Saunders, 1983:276. 11. Melrose RJ, Abrams M, Mills BG. Florid osseous dysplasia: a clinical-pathologic study of thirty-four cases. ORAL SURG ORAL MED ORAL PATHOL 1976;41:62-82. 12. Damm DD, White DK, Drummond JF, Poindexter JB, Henry BB. Combined epithelial odontogenic tumor: adenomatoid odontogenic tumor and calcifying epithelial odontogenic tumor. ORAL SURG ORAL MED ORAL PATHOL 1983;55:487-96. 13. Shear M. Cyst of the oral regions, 3rd ed. Oxford: Wright, 1992. 14. Gardner DG, Kessler HP, Morency R, Schaffner DL. The glandular odontogenic cyst: an apparent entity. J Oral Path01 1988;17:359-66. 15. Craig GT. The paradental cyst: a specific inflammatory odontogenic cyst. Br Dent J 1976;141:9-14. 16. Daley T. The pathology of intraoral sebaceous glands: a review. J Oral Path01 Med 1993;22:241-5. 17. Daley TD, Wysocki GP, Lovas GL, Smout MS. Heterotopic gastric cvst of the oral cavitv. Head Neck 1984:7:168-71. 18. Wysock;GP. The differential diagnosis of globulomaxillary radiolucencies. ORAL SURG ORAL MED ORAL PATHOL 1981; 51:281-6.
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY March 1994 19. Regezi JA, Kerr DA, Courtney RM. Odontogenic tumors. analysis of 706 cases. J Oral Surg 1978;36:771-8 20. Gunhan 0, Erseven G, Ruacan S, et al. Odontogenic turnours: a series of 409 cases. Aust Dent J 1990;35:518-22 21. Bhaskar SN. Oral pathology in the dental office: survey of 20,575 biopsy specimens. J Am Dent Assoc 1968;76:761-6. 22. Mosadomi A. Odontogenic tumors in an African population: analysis of twenty-nine cases seen over a 5-year period. OK~I. SURC ORAL Mm ORAL PATHOL 1975;40:502-21. 23. Wu PC, Chan KW. A survey of tumours of the jawbones in Hong Kong Chinese: 1963-1982. Br J Oral Maxillofac Surg 1985;23:92- 102. 24. Dodge OG. Tumors of the jaw, odontogenic tissues, and maxillary antrum (excluding Burkitt lymphoma) in Uganda Africans. Cancer 1965;18:205-15. 25. Chung DH, Kinnman JEG, Lee BC, Lee YT. Tumors of the jaws in Korea: report of IS7 cases. ORAI. SURG ORAL MED ORAL PATHOL 1969;27:716-28. 26. Kovi J, Laing WN. Tumors of the mandible and maxilla in Accra, Ghana. Cancer 1966;19:1301-7. 21. Thompson CC. A six-year regional report on the oral tumor registry and lesions diagnosed in the School of Dentistry Biopsy Service University of Oregon Health Sciences Center (Portland, Oregon). J Oral Med 1981;36:11-14. 28. Main DMG. Epithelial jaw cysts: a clinicopathological reappraisal. Br J Oral Surg 1970;8:114-25. 29. Killey HC. Kay LW. An analysis of 471 benign cystic lesions of the jaws. Int Surg 1966;46:540-5. 30. Killey HC, Kay LW, Seward GR. Benign cystic lesions of the jaws. their diagnosis and treatment, 3rd ed. Edinburgh: Churchill Livingstone, 1977: 169-70. 31. Radden BG, Reade PC. Odontogenic cysts: a review and a clinicopathological study of 368 odontogenic cysts. Aust Dent J 1973;18:218-25. 32. Hjorting-Hansen E, Andreasen JO, Robinson LH. A study of odontogenic cysts, with special reference to location of keratocysts, Part I. Br J Oral Surg 1969;7:15-23. 33. Weir JC, Davenport WD, Skinner RL. A diagnostic and epidemiology survey of 15,783 oral lesions, J Am Dent Assoc 1987;115:439-42. 34. Baden E. Odontogenic tumors. Path01 Annu 1971;6:475-568. 35. Kim J, Ellis GL. Dental follicular tissue: misinterpretation as odontogenic tumors. J Oral Maxillofac Surg 1993;51:762-7. 36. Cawson RA. Eveson JW. Oral pathology and diagnosis: color atlas with integrated text. Philadelphia: WB Saunders, 1992:5.14. 31. Sciubba JJ. Evaluating dentigerous cysts [letter]. Gen Dent 1991;39:3 13-J. 38. Christ TF. The globulomaxillary cyst: an embryologic misconception. ORAL SURG ORAL MED ORAL PATHOL 1970; 30:515-26. 39. Wysocki GP, Goldblatt Ll. The so-called “globulomaxillary cyst” is extinct. ORAL SURG ORAL MED ORAL PATHOL 1993;76:185-6.
Reprint requests: Tom D. Daley, DDS, MSc, FRCDC Department of Pathology University of Western Ontario London, Ontario, Canada NGA 5Al
OF WESTERN
ONTARIO
The diagnoses of 40,000 consecutively accessioned oral biopsies from the Oral Pathology Diagnostic Service, University of Western Ontario, London, Canada, were reviewed. All odontogenic neoplasms, neoplasm-like lesions (tumors), and true cysts of the oral tissues and jaws were listed. Clinical data were reviewed, and microscopic diagnoses were confirmed for cases in which diagnoses were ambiguous. Records of all caseswere examined to identify distant referrals that were not representative of the study population. Of a total of 445 (1.11%) odontogenic tumors, 392 (0.98%) were lesions from patients in the usual local drawing area of the biopsy service; 53 were referred from distant centers. From the local population, odontomas were by far the most common tumor (51.53%) followed by ameloblastomas (13.52%) and peripheral odontogenic fibromas (8.93%). Locally, radicular (periapical) cysts were the most common odontogenic cyst (65.15%) followed by the dentigerous cyst (24.08%) and the odontogenic keratocyst (4.88%). The most common nonodontogenic cyst was the nasopalatine duct cyst that accounted for 73.43% of this subset of cysts. Surprisingly few studies of this type are available, especially for odontogenic tumors. These data are important to assess geographic differences in the incidence of lesions and to allow clinicians to make realistic judgments in counseling patients before biopsy about the probability of diagnosis and risks associated with nonspecific clinical or radiographic lesions. (ORAL SURC ORAL MED ORAL PATHOI. l!I94;77:276-80)
Records concerning the incidence of most types of neoplasmsare carefully kept by government or health care agenciesin most countries. l-3Thesedata are used to assessthe relative importance of various neoplasms to the well-being of the population and to assessgeographic differences that may lead to clues concerning the causesof these lesions. For example, a disproportionate number of oral squamous cell carcinomas have been found in parts of India, and attempts have been made to relate these data to specific population habits such as betel nut chewing.4,5 However, there is little information on the relative incidence of odontogenie tumors and little more on the incidence of oral and jaw cysts. The records of oral pathology diagnostic servicesare excellent sourcesof such information, despite the inevitable biases that are present in such studies. Nevertheless, information gained from these files is valuable, and probably represents the only large source of such data presently available. The purpose of this study was to determine the incidence of odontogenic tumors, odontogenic cysts, and nonodontogenic cysts of the oral region, relative to all lesions in the biopsy service and relative to one another, and to compare these data with previously published reports from other geographic areas. “Division of Oral Pathology, Department of Pathology. bProfessor and Chairman, Division of Oral Pathology, Department of Pathology. Copyright @ 1994 by Mosby-Year Book, Inc. 0030-4220/94/$3.00 + 0 l/14/52902
276
In this article, the term tumor is used in its generic senseand includes odontogenic neoplasmssuch as the ameloblastoma, hamartomas such as the odontoma, and lesions of uncertain histogenesis such as the peripheral odontogenic fibroma. MATERIAL AND METHODS
The diagnosesof 40,000 consecutively accessioned oral biopsies from the files of the Oral Pathology Diagnostic Service, University of Western Ontario, London, Canada, from 1967 to 1993 were reviewed. AI1 casesof odontogenic tumors, odontogenic cysts, and nonodontogenic cysts were listed. Clinical data and microscopic diagnosesof all casesfor which there was any doubt about the listed diagnoses were reviewed. Most casesbefore 1976 were reviewed to update diagnosesthat resulted from the advancement of knowledge and the definition of new entities. Records from all caseswere reviewed with respect to the contributor of the tissues. All distant referral caseswere separated from casescontributed by clinicians within the local geographic area of the biopsy service that consisted largely of southern Ontario. Odontogenic tumors as described by Regezi and Sciubba,6 the calcifying odontogenic cyst as described by Praetorius et a1.,7peripheral odontogenic fibroma as described by Gardner,8 and primary intraosseous carcinoma as described by Elzay9 were studied. The enameloma as described by Shafer et al. lo was not included because it was considered to be a developmental anomaly. Florid osseousdysplasia as described by Melrose et
Daley. Wysocki, and Pringle
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 77, Number 3 Table
277
I. Odontogenic tumors in 40,000 consecutively accessionedoral biopsies Lesion
Local
Ameloblastoma Calcifying epithelial odontogenic tumor Adenomatoid odontogenic tumor Calcifying odontogenic cyst Squamous odontogenic tumor Clear cell odontogenic tumor Odontogenic carcinoma Odontogenic tumor NOS Central odontogenic fibroma Peripheral odontogenic fibroma Odontogenic myxoma Cementoblastoma Odontogenic sarcoma Ameloblastic ftbroma Ameloblastic tibro-odontoma Odontoma-compound -complex Odontoameloblastoma Dentinoma Ameloblastic fibro-sarcoma TOTAL
53 5 13 18 0 0 1 1 19 35 20 I 0 6 12 128 74 0 0 0 5-2 (0.98%)
Total
Percentage of odontogenic tumors (local only)
19 8 14 18 I 0 I 1 25 36 24 7 0 7 14 130 74 0 0 - 0 445 (1.11%)
13.52 1.28 3.32 4.59 0.00 0.00 0.26 0.26 4.85 8.93 5.10 1.79 0.00 1.53 3.06 32.65 18.88 0.00 0.00 0.00 100.02%
Referrals 26 3 1 0 1 0 6 0 6 1 4 0 0 1 2 2 0 0 0 0 53
NOS = not otherwise specified
al.” and considered to be synonymous with such terms as gigantiform cementoma was not included becauseit was considered to be a nonodontogenic lesion of bone. A similar argument could be made for six casesof periapical cemental dysplasia that were subsequently deleted. Similarly, some pathologists regard the central cementifying fibroma to be a variant of central ossifying fibroma; therefore 50 such caseswere not included in this study. No attempt was made to separate central from peripheral lesions except for the odontogenic fibroma or to separate ameloblastomasinto clinical or histologic types. Combined epithelial odontogenic tumors as described by Damm et a1.t2were classified according to the predominant histologic pattern as calcifying epithelial odontogenic tumor or adenomatoid odontogenic tumor. The simple and World Health Organization types of central odontogenic fibroma were combined. Also studied were cysts as described by Shear,13the glandular odontogenic cyst as described by Gardner et a1.,14the paradental cyst as described by Craig,15 the true sebaceouscyst and the steatocystomasimplex as described by Daley,16 and the heterotopic gastrointestinal cyst as described by Daley et a1.17All globulomaxillary cysts were reviewed and reclassified as described by Wysocki. ‘* Residual radicular cysts were included with radicular cysts. Eruption cysts were separated from dentigerous cysts. Aneurysmal bone cysts and traumatic bone cysts were not included
because they are pseudocyststhat fail to satisfy the definition of a cyst. RESULTS
Tables I, II, and III list the results of this study. DISCUSSION
Despite the obvious need to know the incidence and relative frequency of odontogenic tumors, there are surprisingly few such studies.19M23 In somestudies, the scopeof tumors listed is so limited that a full comparison is impossible.24-27In addition, some of the studies are too old to draw valid comparisons becauseof the definition of new entities and the change in interpretation of other entities.21 There are more studies that addressthe relative frequency of odontogenic and jaw cysts13$ 21,28-33but none from a Canadian population. Again many of these studies are outdated, limited, and not appropriate for comparison.21p32,33 Data from a diagnostic biopsy service are biased in several respects. The relative number of specimens will vary somewhat with the practice of the contributors. A service that receives tissues primarily from endodontists will have a disproportionate number of periapical lesions whereasservicesthat receive tissues primarily from periodontists will seea disproportionate number of gingival lesions. Our biopsy service receives most of its tissues from general dental practioners and oral surgeons. Endodontists, periodon-
278
Daley,
Wysocki,
and Pringle
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY March
I994
II. Odontogenic cysts in 40,000 consecutively accessionedoral biopsies -~--~-~~-7------~-... ~
Table
Lesion
Local
Radicular cyst Dentigerous cyst* Eruption cyst Lateral periodontal cyst Adult gingival cyst Odontogenic keratocyst Cyst of undetermined origin Paradental cyst Glandular odontogenic cyst TOTAL
4461 1649 40 101 33 334 193 33 3 6,847 (17.12%)
Rejzrrals
Total ----.--
_I---.
4468 1662 40 106 33 335 196 33 6 6879 (17.20%)
7
13 0 5 0 I 3 0 3 32
Percentage of odontogmic, cr~tr ilocal onlvj 65.15 24.08 0.58 1.48 0.48 4.88 2.82 0.48 0.04
*see text.
Table
III. Nonodontogenic oral and jaw cysts in 40,000 consecutively accessionedoral biopsies Lesion
Nasopalaline duct cysts Nasolabial cyst Cyst of undetermining origin Median mandibular cyst Benign lympboepithelial cyst Dermoid cyst Epidermoid cyst True sebaceous cyst Steatocystoma simplex Heterotopic gastrointestinal cyst Surgical ciliated cyst Thyroglossal duct cyst TOTAL
Local
Referrals
293 7 1 1 65 1 21 3 1 0 6 0 399 (I .OO%)
tists, oral pathologists, prosthodontists, and medical practitioners also contribute. We believe that a reasonable cross section of tissues is received in our biopsy service, resulting in a reasonably valid relative incidence of lesions. A second source of bias arises from lesions that are diagnosed clinically and radiographically but are not biopsied. For example, our archives contained few casesof periapical cemental dysplasia in part becauseof a justified reluctance to biopsy this condition. A third source of bias results from the inclusion of referrals from distant contributors. These referrals can significantly skew the results becausethey are not representative of the study population. Centers of expertise are likely to have larger numbers of interesting, rare, or diagnostically difficult casesreferred to them. Odontogenic tumors and cysts are commonly referred to oral pathologists by general pathologists. For example, in this study, six of the sevenodontogenic carcinomas were from distant referrals, and 11.91%of all odontogenic tumors studied were from distant centers. To reduce this bias, the geographic location of contributors was determined,
2 0 0 0 1 0 0 0 0 0 0 1 4
Total 295 I 1 1 66 1 21 3 1 0 6 1 403 (1.01%)
Percentage of nonodontogenic cysts (local) 13.43 1.75 0.25 0.25 16.29 0.25 5.26 0.75 0.25 0.00 1.50 0.00
and distant referrals were excluded from percentage calculations (Tables I, II, and III), Additional bias can result from the omission of lesions referred to hospital-based pathology laboratories within the geographic area of the study population. Despite these biases that were corrected whenever possible, we believe that our data is reasonably representative and offers a valid contribution to our knowledge of the relative incidence of these lesions. Regezi et a1.19published a similar study from Michigan, that involved 706 odontogenic tumors derived from 54,534 biopsy specimens, although they did not correct for distant referrals. They found that odontogenic tumors accounted for 1.3%of their biopsies,which is similar to our finding of 1.11%when we include referrals in our series. Local casesaccounted for 0.98% of the 40,000 cases.Table IV lists comparisons in the relative percentages of odontogenic tumors from selected studies. Our sample was also similar to that of Regezi et all9 with regard to reiative incidence of individual odoatogenic tumors. The only notable difference was our incidence of 8.93% for
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 77, Number 3 Table IV.
Daley, Wysocki, and Pringle
279
Comparison of the relative percentage of odontogenic tumors from selected references and this
study Present study
Ameloblastoma Calcifying epithelial odontogenic tumor Adenomatoid odontogenic tumor Calcifying odontogenic cyst Central odontogenic fibroma Peripheral odontogenic fibroma Odontogenic myxoma Periapical cemental dysplasia Ameloblastic fibroma Ameloblastic fibro-odontogenic Odontoma-compound -complex *Combined
Ontario
Regezi et a1.t9 U.S.A.
Gunham et aLzo Turkey
13.52 1.28 3.32 4.59 4.85 8.93 5.10 1.53 3.06 32.65 18.88
11
36.5 1.5 2.5 1.0 4.5 12.5 4.5 1.0 9.0 9.0
Wu and Chan23 Hong Kong 62.19 3.66 2.44 3.66 1.22
2.44 1.22 6.10*
total for complex and compound odontomas.
the peripheral odontogenic fibroma, which was not well defined at the time of their article.” They found a higher relative incidence of odontomas; however, in both studies and in the study by Thompson27in Oregon, odontomas were by far the most common odontogenic tumor. The overall similarity in the incidence of odontogenic tumors may be a reflection of the close geographic proximity of Michigan and Ontario. The study by Gunham et a1.20from Turkey and by Wu and ChanZ3in Hong Kong showed a remarkable geographic variation from our study. The incidences of ameloblastoma were approximately three and six times higher, respectively. Conversely, their incidences of odontomas were approximately five and eight times lower, respectively, than the Ontario study. Whether these differences reflect real geographic variations or are a result of bias is unclear. Nevertheless, the possibility of real geographic variations should be considered, especially in light of the apparently high relative incidence of ameloblastomas in Africa.22l 24,26 Bhaskar’s study21 is outdated and supplies only limited information, although it is still being quoted.20,33,34Understandably, many of the newer entities were not included. In addition, relative percentageswere skewed by the interpretation of hyperplastic dental follicles as central odontgenic fibromas.35 The incidence of odontogenic cysts in this study was similar to that of other studies. These cysts as a group comprised 17.12% of the 40,000 biopsies. The proportion of 65.15% for radicular cysts lies within the range of 52.3% reported by Shear13(although he included nonodontogenic cysts and pseudocysts) and the 77.7% reported by Main.28 Interestingly, Cawson and Eveson arrived at the same 65% figure by combining information from several large seriesin the lit-
erature. Dentigerous cysts were the second most common odontogenic cyst in our series (24.08%) somewhat more than that of Sheari (16.6%), Killey and Kay29(16.2%), and Radden and Reade3’ (17.4%). This difference may reflect the difficulty in diagnosing small dentigerous cysts becauseprecise histologic criteria are not available, and the diagnosis rests largely in the opinion of the operating surgeon. Histologic diagnosis alone is impossible.37A large variation in the relative incidence of odontogenic keratocysts exists between various studies. We found an incidence of 4.88% that contrasts with the findings of Shear13(11.2%) and of Radden and Reade3’ (17.4%). Interestingly, the mean found by Cawson and Eveson36was 7%, which is closer to our findings. The glandular odontogenic cyst is a newly described entity. l4 Our study revealed three local cases and three referred cases,making this cyst a rare lesion relative to other odontogenic cysts. As the lesion becomesmore widely recognized and gains widespread acceptance, its relative incidence may increase. Nonodontogenic cystscomprised 1.O%of the 40,000 biopsies. In agreement with other studies,13T 28,3othe nasopalatine duct cyst was by far the most common and accounted for 73.43% of our cases,whereas the benign lymphoepithelial cyst accounted for 16.29% and epidermoid cysts 5.26%. Other cysts were uncommon. The existence of the globulomaxillary cyst is doubtful.‘*> 38,39 Distant referrals to centers of expertise reflect difficulties in interpretating uncommon or rare lesions. We found most referrals to be in the odontogenic tumor group (11.9 1%) with a high proportion of ameloblastomas and odontogenic carcinomas. Referrals of cysts, on the other hand, represented less than 1% in both the odontogenic and nonodontogenic groups.
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Reprint requests: Tom D. Daley, DDS, MSc, FRCDC Department of Pathology University of Western Ontario London, Ontario, Canada NGA 5Al