- Email: [email protected]
The history of the odontogenic keratocyst
Oral Maxillofacial Surg Clin N Am 15 (2003) 311 – 315
The history of the odontogenic keratocyst M. Anthony Pogrel, DDS, MD, FRCS, FACS Department of Oral and Maxillofacial Surgery, University of California, San Francisco, 521 Parnassus Avenue, Box 0440, San Francisco, CA 94143-0440, USA
Keratinization can occur in the lining of many different types of dental cysts, but there is a specific type in which the keratin is predominantly of the parakeratinizing variety. These cysts are found most commonly at the angles of the mandible, and they have a higher recurrence rate than other types of cysts. Researchers believe that these cysts have been parakeratinized since their formation. Other types of cysts that display keratinization often show the orthokeratinized type, and it is still unclear whether this is caused by metaplasia in response to irritation or they are orthokeratinized from the start. The recurrence rate in these lesions is not believed to be significantly higher than that in nonkeratinized benign dental cysts. Recent immunohistochemical studies have shown fundamental differences between the parakeratinized and orthokeratinized cysts, which suggests that they are different lesions.
[2], and he described several patients who in retrospect had dental cysts. The term ‘‘dentigerous cyst’’ was first suggested by Paget in 1853 [3], although lesions were described previously that seemed to be dentigerous cysts. For example, Jourdain in 1778 [4] described three cases that seemed to be dentigerous cysts. Paget and many subsequent authors used the term ‘‘dentigerous cyst’’ to refer to any cyst of dental origin. The definition of a dentigerous cyst was subsequently refined to its current definition of ‘‘one that develops from the reduced enamel organ after enamel formation had been completed.’’ To be a true dentigerous cyst, the cyst must be derived from the enamel organ and is attached to the amelocemental junction of the tooth and is intimately related to the tooth.
Primordial cysts Cysts in general To examine the history of the odontogenic keratocyst, one must look at the history of cysts of the jaws in general. Cysts were recognized long before the invention of x-rays in 1896, which is probably the most frequent method of diagnosing cysts currently. Many early authors described ‘‘tumors’’ or other lesions of the jaws, which in retrospect were almost certainly cysts but were not recognized or named as such. John Hunter, the noted anatomist, published a monograph in 1774 that seems to describe a patient with a dental cyst [1]. Similarly, Fauchard published many classic articles on dental pathology in French
E-mail address: [email protected]
The term ‘‘primordial cyst’’ was first mentioned in 1945 by Robinson [5] because the cysts were believed to have a more primordial origin because they arose from remnants of the dental lamina or the enamel organs before enamel formation had taken place. Researchers believed that they either replaced a missing tooth or a supernumerary tooth and were most frequently found in the posterior mandible, possibly replacing a third molar. Robinson’s paper [5] was first presented at the 22nd General Meeting of the International Association for Dental Research in Chicago on March 18, 1944. The classification in this paper was a modification of those previously used and was arrived at after active consultation with many of the leading pathologists and surgeons at that time. In this classification, odontogenic cysts were subdivided into periodontal
1042-3699/03/$ – see front matter D 2003 Elsevier Inc. All rights reserved. doi:10.1016/S1042-3699(03)00031-1
312
M.A. Pogrel / Oral Maxillofacial Surg Clin N Am 15 (2003) 311–315
cysts, dentigerous cysts, and primordial cysts. The primordial cyst was believed to arise from degeneration of the enamel organ before formation of enamel, and it replaced a tooth. This concept was recognized before 1945, but it was called a ‘‘simple cyst,’’ which denoted an origin from simple or primitive odontogenic tissues. Robinson, in an earlier classification published in 1937 [6], subdivided dentigerous cysts into simple, compound, eruption, and heterotropic categories. The first mention of a ‘‘simple cyst’’ may be by Geschickter in 1935, who mentioned a ‘‘simple follicular cyst [7].’’ In 1949, Thoma [8] subdivided follicular cysts into the following categories: primordial or simple (without tooth formation), dentigerous, with odontoma, and multiple. In 1937, in an earlier edition of his textbook, Thoma [9] subdivided follicular cysts into the categories of simple (without tooth formation), dentigerous, and with odontoma.
Follicular cyst Between the terms ‘‘dentigerous cyst’’ and ‘‘primordial cyst’’ was the term ‘‘follicular cyst.’’ This term has largely disappeared from the literature, but it was applied to any cyst believed to be derived from the dental follicle. In reviewing previous articles, it was originally applied to dentigerous cysts and primordial cysts. Later authors tended to make the follicular cyst synonymous with dentigerous cyst. Shear [10], in his classic monograph, certainly believed that the dentigerous cyst and follicular cyst were synonymous.
The recurrence rate of cysts Since the 1950s, investigators have noted that dental cysts occasionally recur after surgical removal. F. Gordon Hardman, Consultant Oral and Maxillofacial Surgeon in North Wales from 1953 to 1984, was quoted as saying ‘‘We always knew some cysts recurred so the patient came to have them curetted out every 5 – 10 years. So what!! We never had to give them separate names.’’ When large series of cysts were reviewed, it seemed that the recurrence rate was usually quoted as less than 6%. For example, Fickling, in his presentation to the Royal College of Physicians in 1965 [11], noted an overall recurrence rate in his series of 5.6%. Rarely were these recurrences subdivided, but when they were, a high rate of recurrence and even multiple recurrences in the group classified
as primordial cysts appeared [12], although the authors did not comment often on this matter [11,13].
Keratinization Since the 1930s, investigators have noted that dental cysts could be found with keratinization in the lining of the cyst and keratin itself in the cyst contents [14,15]. In 1956, Phillipsen [16] published an article in Danish with a summary in English that drew this together and first suggested the term ‘‘odontogenic keratocyst.’’ In his article he meant this to refer to all odontogenic cysts, regardless of type, that showed keratinization (parakeratinization or orthokeratinization) in the epithelium. The terminology included keratinized cysts that were previously described under such terms as ‘‘epidermoid cysts of the jaws’’ [17], jaw cholesteatomas [18], and multiple cysts of the jaws [19]. At that time, studies showed that keratinization could be found in the lining of approximately 3% to 5% of all dental cysts [12,20]. It did not seem to be noted that keratinization appeared more frequently—or almost exclusively—in the entity referred to as a primordial cyst. In 1963, Pindborg and Hansen [21] reported on 30 odontogenic kertocysts but believed that 17 were residual cysts, 7 were dentigerous cysts, and 4 were related to teeth but not apparently connected. When primordial cysts were examined as a separate group, it was noticed that they were routinely keratinized, although early articles often stated that keratinization could be either parakeratotic or orthokeratotic [22]. As studies increased, however, the consensus seemed to shift to the opinion that the type of keratinization seen in the primordial cyst was almost always parakeratin. Researchers recognized, however, that keratinization could occur in other types of cysts but that this type of keratinization was often orthokeratin. Phillipsen [16], in his classic article in 1956, believed that the presence of keratinization in a cyst represented a further stage of development beyond a nonkeratinized cyst. Researchers currently do not hold this same belief, particularly with the equivalent of the primordial cyst, in which it is believed that they have been parakeratinized at all stages of development. The origin of the orthokeratin in other types of cysts still has not been elucidated fully, however. Investigators believed that this could occur from metaplasia of nonkeratinized cyst epithelium, particularly in the presence of inflammation [23]. Researchers often noted that orthokeratinized cysts had a higher rate of inflammation as judged by inflammatory cells than
M.A. Pogrel / Oral Maxillofacial Surg Clin N Am 15 (2003) 311–315
the parakeratinized version that appeared more commonly in the primordial cyst.
Malignant potential of dental cysts Isolated reports have appeared over the years regarding possible malignant change in previously benign dental cysts [23 – 25]. Whether the lesion was malignant from the beginning or whether a benign cyst can undergo malignant transformation is a subject of controversy. When the odontogenic keratocyst was described as a variant among dental cysts, it was believed that its malignant potential may be greater than with other cysts [23], and it was suggested that the orthokeratinized version, which may have arisen by metaplasia in the presence of infection, may have an even higher malignant transformation rate because of the additional factors. This is no longer believed to be the case, and malignant change in dental cysts of all types is believed to be rare. Its prevention is not necessarily a justification for cyst removal.
Putting it all together By the 1960s, researchers had all the elements necessary to put the story together. The concept of the primordial cyst arising from undifferentiated dental lamina was proposed. The concept that some cysts can recur also was proposed, and the concept was proposed that the recurrence rate in primordial cysts may be somewhat higher than in other dental cysts. The fact that a small proportion of cysts contained keratinized linings also was noted. Researchers noted that this was more common in the primordial cyst and that the type of keratin in the primordial was predominantly parakeratin. In 1960, in his classic article on the primordial cyst, Shear [22] stated that the presence of keratin in a cyst lining was of academic interest only and of no clinical significance. Articles by Browne [26,27] in 1970 and 1971 provided considerable clarification to these issues. He examined the relationship between the keratinized cyst and the crowns of the teeth and found that in few cases were they truly dentigerous cysts. In most cases, although they were often related to the crown of a tooth or displaced crown of the tooth, they were not truly dentigerous because they did not seem to have been derived from the reduced enamel organ and were not attached to the tooth at the amelocemental junction. The fact that they also
313
commonly occurred at the angles of the mandible caused him to equate most of them with the primordial cyst. Browne recommended that the term ‘‘primordial cyst’’ be eliminated in favor of the neutral term ‘‘odontogenic keratocyst’’ because it did not address the controversial issues of the origin or derivation of the cyst itself but dwelt on its histologic features that he believed defined its clinical behavior and higher recurrence rate. Browne confirmed the higher recurrence rate of these lesions from other cysts and suggested that it was caused by an inherent property of the cysts themselves rather than the technique of removal. Before this, some authors recognized that the cyst often had a thin lining if it was not inflamed and suggested that recurrences may be caused by inadequate removal of this thin lining rather than any innate properties of the cyst itself [28]. After the articles by Browne, many authors believed that the odontogenic keratocyst and the primordial cyst were one and the same lesion, and the terms were interchangeable. Other authors believed that they should be separated and that the primordial cyst represented only the odontogenic keratocysts that were parakeratinized. In 1971, the World Health Organization recognized the concept that the primordial cyst and the odontogenic keratocyst were synonymous [29] and emphasized histologic features rather than the possible origin from the primordial dental lamina. The term ‘‘primordial cyst’’ seems to have disappeared from the literature, although it could be found until the late 1980s [30].
Multiple dental cysts Multiple dental cysts have been noted in the literature since the 1930s and were often referred to as follicular cysts [31,32]. The fact that these multiple cysts could recur also was noted [33]. The relationship with other abnormalities also has been noted, but it was left to Gorlin and Goltz [34] in 1960 to tie all of this together into the syndrome that currently bears their name. In the article, they described the relationship of primordial cysts of the jaws with skeletal abnormalities, including bifid ribs, hand and foot abnormalities, and skin abnormalities, including basal cell carcinomas, palmar pitting, and various skin tags. Later authors recognized that the cysts found in the syndrome are the parakeratinized type of odontogenic keratocyst and that there are additional manifestations of the syndrome [35].
314
M.A. Pogrel / Oral Maxillofacial Surg Clin N Am 15 (2003) 311–315
Summary Over a period of more than 100 years, we have arrived at the conclusion that keratinization can occur in the lining of many different types of dental cysts but that there is a specific type in which the keratin is predominantly of the parakeratinizing variety. They are found most commonly at the angles of the mandible, with or without a relationship to the crown of the tooth, and these cysts have a higher recurrence rate than other types of cysts. Researchers believe that these cysts have been parakeratinized since their formation. Other types of cysts that display keratinization often show the orthokeratinized type, and it is still unclear whether this is caused by metaplasia in response to irritation or they are orthokeratinized from the start. The recurrence rate in these lesions is not believed to be significantly higher than that in nonkeratinized benign dental cysts [36,37]. Recent immunohistochemical studies have shown fundamental differences between the parakeratinized and orthokeratinized cysts, which suggests that they are different lesions [38 – 40].
References [1] Hunter J. The natural history of the human teeth. London: Johnson; 1774. [2] Fauchard P. Le chirurgien dentiste. Paris: 1728. p. 357. [3] Paget J. Lectures on surgical pathology. London: 1853. p. 90. [4] Jourdain E. Traite des maladies de la bouche. Paris: 1778. p. 19. [5] Robinson HBG. Classification of cysts of the jaws. Am J Ortho Oral Surg 1945;31:370 – 5. [6] Robinson HBG. Ameloblastoma. Arch Pathol 1937;23: 831 – 43. [7] Geschickter CF. Tumors of jaws. Am J Cancer 1935; 24:90 – 126. [8] Thoma KH. Oral and dental diagnosis. Philadelphia: WB Saunders; 1949. p. 438. [9] Thoma KH. Oral diagnosis and treatment planning. Philadelphia: WB Saunders; 1937. p. 286. [10] Shear M. Cysts of the oral regions. Bristol: John Wright & Sons Ltd.; 1976. p. 42. [11] Fickling B. Cysts of the jaws: a long term survey of types and treatment. Annals of the Royal College of Physicians 1965;58: 847 – 54. [12] Bramley PA, Brown RM. Recurring odontogenic cysts. Br J Oral Surg 1967;5:106 – 16. [13] Archer WH. A manual of oral surgery. Philadelphia: WB Saunders; 1956. p. 297. [14] Dowsett EB. Unique dental cyst. Proc R Soc Med 1933; 26:1562.
[15] Hewer TF. Primary epithelial tumors of the jaws. J Clin Pathol 1952;5:225 – 33. [16] Phillipsen HP. OM Keratocyster (kolestea-tomer). I. Kaeberne. Tandiaegebladet 1956;60:963 – 80. ¨ ber einen fall von epidermoidzyste des [17] Brosch F. U unterkiefers. Deutsch Zahnartz Wochenschr 1938;41: 1020 – 2. [18] Hauer A. Ein cholesteatch im linken unterkiefer unter einem retiwierten weisheitszahn. J Stomatol 1926;24: 40 – 9. [19] Schafstein IWL. Multiple cysts of the jaws. Am J Orthod Oral Surg 1943;29:452 – 6. [20] Toller PA. Origin and growth of cysts of the jaw. Ann R Coll Surg Engl 1967;40:306 – 36. [21] Pindborg JJ, Hansen J. Studies on odontogenic epithelium. Acta Pathol Microbiol Scand 1963;58: 283 – 94. [22] Shear M. Primordial csysts. J Dent Assoc S Afr 1960; 15:211 – 7. [23] Browne R, Gough NG. Malignant change in the epithelium lining odontogenic cysts. Cancer 1972;29: 1199 – 207. [24] Hardman FG. Carcinomata arising in dental cysts. Br J Oral Surg 1963;1:124 – 31. [25] Anand VK, Arrowood JP, Krous SO. Malignant potential of the odontogenic keratocyst. Otolaryngol Head Neck Surg 1994;111:124 – 9. [26] Browne RM. The odontogenic keratocyst: clinical aspects. Br Dent J 1970;128:225 – 31. [27] Browne RM. The odontogenic keratocyst: histological features and their correlation with clinical behavior. Br Dent J 1971;129:249 – 59. [28] Brady CL, Browne RM, Calverley BC, Jones MS, Marsland EA, Whitehead FIH. Symposium on odontogenic epithelium. Br J Oral Surg 1970;8:1 – 15. [29] World Health Organization. International classification of tumours. Number 5: Histological typing of odontogenic tumours, jaw cysts and allied lesions. Geneva: World Health Organization; 1971. p. 19. [30] Partridge M, Towers JF. The primordial cyst (odontogenic keratocyst): its tumor-like characteristics and behavior. Br J Oral Maxillofac Surg 1987;25:271 – 9. [31] Knight JS, Manley BB. A case of multiple cysts of the mandible. Br Dent J 1951;91:209 – 15. [32] Gross PP. Epithelioma adenoides cysticum with follicular cysts of maxilla and mandible. J Oral Surg 1953;11: 160 – 5. [33] Cantania AF. Report and comment on an unusual case of multiple follicular cysts with a recurrence. Oral Surg 1952;5:895 – 906. [34] Gorlin RJ, Goltz RW. Multiple nevoid basal cell carcinoma, jaw cysts and bifid ribs: a syndrome. N Engl J Med 1960;262:908 – 12. [35] Gorlin RJ, Vickers RA, Keller E, Williamson JJ. The multiple basal cell nevi syndrome. Cancer 1965;18: 89 – 104. [36] Wright JM. The odontogenic keratocyst: orthokeratinized version. Oral Surg 1981;51:609 – 18. [37] Crowley TE, Kaugars GE, Gunsolley JC. Odontogenic
M.A. Pogrel / Oral Maxillofacial Surg Clin N Am 15 (2003) 311–315 keratocysts: a clinical and histologic comparison of the parakeratin and orthokeratin variants. J Oral Maxillofac Surg 1992;50:22 – 6. [38] Shear M. The aggressive nature of the odontogenic keratocyst: is it a benign cystic neoplasm. Part 1. Oral Oncol 2002;38:219 – 26.
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[39] Shear M. The aggressive nature of the odontogenic keratocyst: is it a benign cystic neoplasm. Part II. Oral Oncol 2002;38:323 – 31. [40] Shear M. The aggressive nature of the odontogenic keratocyst: is it a benign cystic neoplasm. Part III. Oral Oncol 2002;38:407 – 15.
The history of the odontogenic keratocyst M. Anthony Pogrel, DDS, MD, FRCS, FACS Department of Oral and Maxillofacial Surgery, University of California, San Francisco, 521 Parnassus Avenue, Box 0440, San Francisco, CA 94143-0440, USA
Keratinization can occur in the lining of many different types of dental cysts, but there is a specific type in which the keratin is predominantly of the parakeratinizing variety. These cysts are found most commonly at the angles of the mandible, and they have a higher recurrence rate than other types of cysts. Researchers believe that these cysts have been parakeratinized since their formation. Other types of cysts that display keratinization often show the orthokeratinized type, and it is still unclear whether this is caused by metaplasia in response to irritation or they are orthokeratinized from the start. The recurrence rate in these lesions is not believed to be significantly higher than that in nonkeratinized benign dental cysts. Recent immunohistochemical studies have shown fundamental differences between the parakeratinized and orthokeratinized cysts, which suggests that they are different lesions.
[2], and he described several patients who in retrospect had dental cysts. The term ‘‘dentigerous cyst’’ was first suggested by Paget in 1853 [3], although lesions were described previously that seemed to be dentigerous cysts. For example, Jourdain in 1778 [4] described three cases that seemed to be dentigerous cysts. Paget and many subsequent authors used the term ‘‘dentigerous cyst’’ to refer to any cyst of dental origin. The definition of a dentigerous cyst was subsequently refined to its current definition of ‘‘one that develops from the reduced enamel organ after enamel formation had been completed.’’ To be a true dentigerous cyst, the cyst must be derived from the enamel organ and is attached to the amelocemental junction of the tooth and is intimately related to the tooth.
Primordial cysts Cysts in general To examine the history of the odontogenic keratocyst, one must look at the history of cysts of the jaws in general. Cysts were recognized long before the invention of x-rays in 1896, which is probably the most frequent method of diagnosing cysts currently. Many early authors described ‘‘tumors’’ or other lesions of the jaws, which in retrospect were almost certainly cysts but were not recognized or named as such. John Hunter, the noted anatomist, published a monograph in 1774 that seems to describe a patient with a dental cyst [1]. Similarly, Fauchard published many classic articles on dental pathology in French
E-mail address: [email protected]
The term ‘‘primordial cyst’’ was first mentioned in 1945 by Robinson [5] because the cysts were believed to have a more primordial origin because they arose from remnants of the dental lamina or the enamel organs before enamel formation had taken place. Researchers believed that they either replaced a missing tooth or a supernumerary tooth and were most frequently found in the posterior mandible, possibly replacing a third molar. Robinson’s paper [5] was first presented at the 22nd General Meeting of the International Association for Dental Research in Chicago on March 18, 1944. The classification in this paper was a modification of those previously used and was arrived at after active consultation with many of the leading pathologists and surgeons at that time. In this classification, odontogenic cysts were subdivided into periodontal
1042-3699/03/$ – see front matter D 2003 Elsevier Inc. All rights reserved. doi:10.1016/S1042-3699(03)00031-1
312
M.A. Pogrel / Oral Maxillofacial Surg Clin N Am 15 (2003) 311–315
cysts, dentigerous cysts, and primordial cysts. The primordial cyst was believed to arise from degeneration of the enamel organ before formation of enamel, and it replaced a tooth. This concept was recognized before 1945, but it was called a ‘‘simple cyst,’’ which denoted an origin from simple or primitive odontogenic tissues. Robinson, in an earlier classification published in 1937 [6], subdivided dentigerous cysts into simple, compound, eruption, and heterotropic categories. The first mention of a ‘‘simple cyst’’ may be by Geschickter in 1935, who mentioned a ‘‘simple follicular cyst [7].’’ In 1949, Thoma [8] subdivided follicular cysts into the following categories: primordial or simple (without tooth formation), dentigerous, with odontoma, and multiple. In 1937, in an earlier edition of his textbook, Thoma [9] subdivided follicular cysts into the categories of simple (without tooth formation), dentigerous, and with odontoma.
Follicular cyst Between the terms ‘‘dentigerous cyst’’ and ‘‘primordial cyst’’ was the term ‘‘follicular cyst.’’ This term has largely disappeared from the literature, but it was applied to any cyst believed to be derived from the dental follicle. In reviewing previous articles, it was originally applied to dentigerous cysts and primordial cysts. Later authors tended to make the follicular cyst synonymous with dentigerous cyst. Shear [10], in his classic monograph, certainly believed that the dentigerous cyst and follicular cyst were synonymous.
The recurrence rate of cysts Since the 1950s, investigators have noted that dental cysts occasionally recur after surgical removal. F. Gordon Hardman, Consultant Oral and Maxillofacial Surgeon in North Wales from 1953 to 1984, was quoted as saying ‘‘We always knew some cysts recurred so the patient came to have them curetted out every 5 – 10 years. So what!! We never had to give them separate names.’’ When large series of cysts were reviewed, it seemed that the recurrence rate was usually quoted as less than 6%. For example, Fickling, in his presentation to the Royal College of Physicians in 1965 [11], noted an overall recurrence rate in his series of 5.6%. Rarely were these recurrences subdivided, but when they were, a high rate of recurrence and even multiple recurrences in the group classified
as primordial cysts appeared [12], although the authors did not comment often on this matter [11,13].
Keratinization Since the 1930s, investigators have noted that dental cysts could be found with keratinization in the lining of the cyst and keratin itself in the cyst contents [14,15]. In 1956, Phillipsen [16] published an article in Danish with a summary in English that drew this together and first suggested the term ‘‘odontogenic keratocyst.’’ In his article he meant this to refer to all odontogenic cysts, regardless of type, that showed keratinization (parakeratinization or orthokeratinization) in the epithelium. The terminology included keratinized cysts that were previously described under such terms as ‘‘epidermoid cysts of the jaws’’ [17], jaw cholesteatomas [18], and multiple cysts of the jaws [19]. At that time, studies showed that keratinization could be found in the lining of approximately 3% to 5% of all dental cysts [12,20]. It did not seem to be noted that keratinization appeared more frequently—or almost exclusively—in the entity referred to as a primordial cyst. In 1963, Pindborg and Hansen [21] reported on 30 odontogenic kertocysts but believed that 17 were residual cysts, 7 were dentigerous cysts, and 4 were related to teeth but not apparently connected. When primordial cysts were examined as a separate group, it was noticed that they were routinely keratinized, although early articles often stated that keratinization could be either parakeratotic or orthokeratotic [22]. As studies increased, however, the consensus seemed to shift to the opinion that the type of keratinization seen in the primordial cyst was almost always parakeratin. Researchers recognized, however, that keratinization could occur in other types of cysts but that this type of keratinization was often orthokeratin. Phillipsen [16], in his classic article in 1956, believed that the presence of keratinization in a cyst represented a further stage of development beyond a nonkeratinized cyst. Researchers currently do not hold this same belief, particularly with the equivalent of the primordial cyst, in which it is believed that they have been parakeratinized at all stages of development. The origin of the orthokeratin in other types of cysts still has not been elucidated fully, however. Investigators believed that this could occur from metaplasia of nonkeratinized cyst epithelium, particularly in the presence of inflammation [23]. Researchers often noted that orthokeratinized cysts had a higher rate of inflammation as judged by inflammatory cells than
M.A. Pogrel / Oral Maxillofacial Surg Clin N Am 15 (2003) 311–315
the parakeratinized version that appeared more commonly in the primordial cyst.
Malignant potential of dental cysts Isolated reports have appeared over the years regarding possible malignant change in previously benign dental cysts [23 – 25]. Whether the lesion was malignant from the beginning or whether a benign cyst can undergo malignant transformation is a subject of controversy. When the odontogenic keratocyst was described as a variant among dental cysts, it was believed that its malignant potential may be greater than with other cysts [23], and it was suggested that the orthokeratinized version, which may have arisen by metaplasia in the presence of infection, may have an even higher malignant transformation rate because of the additional factors. This is no longer believed to be the case, and malignant change in dental cysts of all types is believed to be rare. Its prevention is not necessarily a justification for cyst removal.
Putting it all together By the 1960s, researchers had all the elements necessary to put the story together. The concept of the primordial cyst arising from undifferentiated dental lamina was proposed. The concept that some cysts can recur also was proposed, and the concept was proposed that the recurrence rate in primordial cysts may be somewhat higher than in other dental cysts. The fact that a small proportion of cysts contained keratinized linings also was noted. Researchers noted that this was more common in the primordial cyst and that the type of keratin in the primordial was predominantly parakeratin. In 1960, in his classic article on the primordial cyst, Shear [22] stated that the presence of keratin in a cyst lining was of academic interest only and of no clinical significance. Articles by Browne [26,27] in 1970 and 1971 provided considerable clarification to these issues. He examined the relationship between the keratinized cyst and the crowns of the teeth and found that in few cases were they truly dentigerous cysts. In most cases, although they were often related to the crown of a tooth or displaced crown of the tooth, they were not truly dentigerous because they did not seem to have been derived from the reduced enamel organ and were not attached to the tooth at the amelocemental junction. The fact that they also
313
commonly occurred at the angles of the mandible caused him to equate most of them with the primordial cyst. Browne recommended that the term ‘‘primordial cyst’’ be eliminated in favor of the neutral term ‘‘odontogenic keratocyst’’ because it did not address the controversial issues of the origin or derivation of the cyst itself but dwelt on its histologic features that he believed defined its clinical behavior and higher recurrence rate. Browne confirmed the higher recurrence rate of these lesions from other cysts and suggested that it was caused by an inherent property of the cysts themselves rather than the technique of removal. Before this, some authors recognized that the cyst often had a thin lining if it was not inflamed and suggested that recurrences may be caused by inadequate removal of this thin lining rather than any innate properties of the cyst itself [28]. After the articles by Browne, many authors believed that the odontogenic keratocyst and the primordial cyst were one and the same lesion, and the terms were interchangeable. Other authors believed that they should be separated and that the primordial cyst represented only the odontogenic keratocysts that were parakeratinized. In 1971, the World Health Organization recognized the concept that the primordial cyst and the odontogenic keratocyst were synonymous [29] and emphasized histologic features rather than the possible origin from the primordial dental lamina. The term ‘‘primordial cyst’’ seems to have disappeared from the literature, although it could be found until the late 1980s [30].
Multiple dental cysts Multiple dental cysts have been noted in the literature since the 1930s and were often referred to as follicular cysts [31,32]. The fact that these multiple cysts could recur also was noted [33]. The relationship with other abnormalities also has been noted, but it was left to Gorlin and Goltz [34] in 1960 to tie all of this together into the syndrome that currently bears their name. In the article, they described the relationship of primordial cysts of the jaws with skeletal abnormalities, including bifid ribs, hand and foot abnormalities, and skin abnormalities, including basal cell carcinomas, palmar pitting, and various skin tags. Later authors recognized that the cysts found in the syndrome are the parakeratinized type of odontogenic keratocyst and that there are additional manifestations of the syndrome [35].
314
M.A. Pogrel / Oral Maxillofacial Surg Clin N Am 15 (2003) 311–315
Summary Over a period of more than 100 years, we have arrived at the conclusion that keratinization can occur in the lining of many different types of dental cysts but that there is a specific type in which the keratin is predominantly of the parakeratinizing variety. They are found most commonly at the angles of the mandible, with or without a relationship to the crown of the tooth, and these cysts have a higher recurrence rate than other types of cysts. Researchers believe that these cysts have been parakeratinized since their formation. Other types of cysts that display keratinization often show the orthokeratinized type, and it is still unclear whether this is caused by metaplasia in response to irritation or they are orthokeratinized from the start. The recurrence rate in these lesions is not believed to be significantly higher than that in nonkeratinized benign dental cysts [36,37]. Recent immunohistochemical studies have shown fundamental differences between the parakeratinized and orthokeratinized cysts, which suggests that they are different lesions [38 – 40].
References [1] Hunter J. The natural history of the human teeth. London: Johnson; 1774. [2] Fauchard P. Le chirurgien dentiste. Paris: 1728. p. 357. [3] Paget J. Lectures on surgical pathology. London: 1853. p. 90. [4] Jourdain E. Traite des maladies de la bouche. Paris: 1778. p. 19. [5] Robinson HBG. Classification of cysts of the jaws. Am J Ortho Oral Surg 1945;31:370 – 5. [6] Robinson HBG. Ameloblastoma. Arch Pathol 1937;23: 831 – 43. [7] Geschickter CF. Tumors of jaws. Am J Cancer 1935; 24:90 – 126. [8] Thoma KH. Oral and dental diagnosis. Philadelphia: WB Saunders; 1949. p. 438. [9] Thoma KH. Oral diagnosis and treatment planning. Philadelphia: WB Saunders; 1937. p. 286. [10] Shear M. Cysts of the oral regions. Bristol: John Wright & Sons Ltd.; 1976. p. 42. [11] Fickling B. Cysts of the jaws: a long term survey of types and treatment. Annals of the Royal College of Physicians 1965;58: 847 – 54. [12] Bramley PA, Brown RM. Recurring odontogenic cysts. Br J Oral Surg 1967;5:106 – 16. [13] Archer WH. A manual of oral surgery. Philadelphia: WB Saunders; 1956. p. 297. [14] Dowsett EB. Unique dental cyst. Proc R Soc Med 1933; 26:1562.
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