Dentomaxillofacial Radiology (2006) 35, 60-64
© 2006 British Institute of Radiology
doi: 10.1259/dmfr/66396640
Probable keratocyst in a mandible from the late Roman era
E Chimenos-Küstner*,1 and
B Agustí-Farjas2
1 Faculty of Odontology, University of Barcelona, Barcelona, Spain;
2 University of Girona, Girona, Spain
*Correspondence to: Eduardo Chimenos-Küstner, V
a Augusta 124, 1° 3a, 08006 – Barcelona, Spain; E-mail: 13598eck{at}comb.es
Received 17 January 2005;
accepted 20 April 2005
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Abstract
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Odontogenic keratocysts, characterized by considerable local aggressiveness and high recurrence rates, account for 5–15% of all odontogenic cysts. This paper reviews the literature and describes the most important aspects of this type of cyst, a clinical example being given as way of illustration. We also report a paleopathological case featuring an osteolytic lesion where the characteristics are consistent with a keratocyst. The aim is thus to encourage odontologists to contribute to research in the field of paleopathology.
Keywords: keratocyst; differential diagnosis; odontogenic cysts; paleopathology
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Introduction
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Odontogenic keratocysts (OKCs) are clinically and histologically distinct from other odontogenic cysts. They are characterized by aggressive clinical behaviour and high recurrence rates, and may appear as part of a nevoid basal cell carcinoma (or Gorlin-Goltz) syndrome. Recent research has suggested that the molecular origin of OKCs may be loss of the human tumour suppressor gene patched (PTCH).1
These odontogenic cysts develop from dental lamina remnants and, theoretically, may appear anywhere in the jaws; however, two-thirds of cases affect the mandible, particularly the posterior part of the body and the ascending ramus (Figure 1
). OKCs sometimes develop around the crown of a non-erupted tooth, as if they were dentigerous cysts, and consequently some authors have suggested that this kind of OKC has fused with a pre-existing dentigerous cyst.2
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Figure 1 Detail of a panoramic radiograph showing the extension of a keratocyst through the body and the ascending mandibular ramus, in a woman aged 30 years
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Although the lesion is usually isolated there may be multiple cysts, distributed around the four quadrants of the jaws.2 They may grow to a great size and cause massive bone damage, which can, on occasion, perforate the cortical bone (Figures 1 and 2
). Maxillary lesions most often appear in the posterior segment or in the lateral incisor-canine area. Their rate of recurrence ranges from 25% to 60%, similar to the rate for ameloblastomas and very different from the figure for other odontogenic cysts. Although most OKCs are intraosseous lesions, they may occasionally have an extraosseous location in the layers of gingival soft tissue. These rare clinical forms are known as peripheral OKCs.2
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Figure 2 Clinical image of the same case as in Figure 1, showing the cyst in contact with the exterior, having perforated the cortical bone, periosteum and mucosa
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OKCs account for 5–15% of all odontogenic cysts, although those associated with nevoid basal cell syndrome are less common than their sporadic counterparts.1
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Clinical aspects
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The age at which OKCs appear varies greatly, from the first to the eighth decade of life. However, they are more frequently found between the second and fourth decades. They may present as single or multiple osseous lesions and can be small or extensive, unilateral or bilateral, and unilocular or multilocular in addition to the peripheral forms mentioned above. Their capacity for destruction and invasion, coupled with their high rate of recurrence, makes them the most aggressive of all odontogenic cysts. The most common presentation is a single extensive multilocular lesion located in the posterior region of the mandible and appearing around the third decade of life. If they are not treated, these lesions can spread throughout the ascending mandibular ramus or cause expansion of the jaws.1
Although they are usually asymptomatic, they may cause discrete inflammation and can be painful if there is a secondary superinfection. Aspiration of their content reveals a thick, yellow, creamy material composed of keratin (Figure 2). It is important to note that, unlike other cysts, OKCs have a high recurrence rate, possibly due to the small satellite cysts or epithelial fragments which remain following surgical resection of the cyst.3
The presence of multiple OKCs, along with other characteristics, is a constant feature of nevoid basal cell syndrome, an autosomal dominant disorder of high penetration and variable expression. Over 100 characteristics of this syndrome have been described, although they are not always found in all patients.1,2 Table 1 provides a summary of the most common characteristics.2
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Radiological aspects
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It has already been pointed out that OKCs are most commonly located in the posterior part of the mandibular body (90% of lesions are located distal to the canines and 50% reach the ascending ramus). Their centre is situated over the canal of the inferior dental nerve. In terms of their radiological appearance they are sometimes, when surrounding the crown of a tooth, identical to dentigerous cysts.
Provided there is no secondary infection, OKCs are commonly surrounded by a cortical margin (usually thicker than in other cysts). They are usually oval or round, and may have a scalloped margin. Their internal structure is usually radiolucent, and the presence of keratin within does not increase their radiopacity. If there are curved septa inside then they may adopt a multilocular form, as occurs with some ameloblastomas.
It is important to note their propensity to grow inside the jaws, more often in a longitudinal than a transverse direction (minimum expansion). However, they show a greater tendency to expand in the ascending ramus and the coronoid process, where the cortical bone is thinner. The size of some large cysts prevents the periosteum from forming new bone around the cyst, such that the latter enters into contact with the soft tissue peripheral to the external cortical bone, or may even perforate it (Figure 2). Given that the expansion which usually occurs is barely noticeable, diagnosis tends to be made late and this accounts for the large size reached by such cysts (Figure 1). OKCs may displace and resorb teeth, although to a lesser extent than dentigerous cysts. They may also displace the dental canal downwards. In the maxilla they may completely occupy the maxillary antrum.3
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Differential radiological diagnosis
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An OKC in the pericoronal position is indistinguishable from a dentigerous cyst. It is more likely to be an OKC if it is attached to the tooth at the apical part of the amelocemental junction,3 or if there is no expansion of the cortical bones. The scalloped margin and multilocular appearance are reminiscent of an ameloblastoma, although the latter is more likely to expand. The characteristics of moderate expansion and multilocular appearance may lead the OKC to resemble an odontogenic myxoma. Although simple bone cysts also commonly present a scalloped margin and minimum bone expansion, their margins are more difficult to detect than those of an OKC. The existence of several OKCs should lead the clinician to consider a nevoid basal cell syndrome.3
Given that these cysts tend to recur it is important to make the differential diagnosis, even if they are not large at the time of diagnosis. To this end, and in order to adopt the most suitable diagnostic and therapeutic measures in each case, the clinician should take into account the general (not only radiological) principles of differential diagnosis summarized in Table 2.4,5 Aspiration of the contents of the lesion may be of great help in reaching a diagnosis.
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Histopathological diagnosis
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The microscopic appearance of OKCs is diagnostic. The cyst cavity shows the following features:1,2- A thin and uniform lining of orthokeratinised or parakeratinised squamous epithelium, 3–10 cells in thickness
- Palisade layer of prismatic or cuboid basal cells
- Corrugated or crimped parakeratin layer on the luminal surface
- Absence of epithelial papillae
- The cyst wall shows nicks produced by cholesterol crystals, inflammatory cells, calcifications and satellite microcysts
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Treatment
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This consists of surgical removal using one or more of the following methods: curettage, complete enucleation and subsequent treatment with Carnoy's solution or cryotherapy, radical enucleation of the cyst and curettage of peripheral tissue, marsupialization, or resection, with removal of a mandibular or maxillary fragment.1,6
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Description of the paleopathological case
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The mandible studied came from a tomb that forms part of a set of individual burial deposits, situated inside the funerary site attached to the pre-Romanesque church of Santa Magdalena de Empúries (l'Escala, Girona, Catalonia, Spain), which dates back to between the 5th and 10th centuries. The funerary level was excavated in 2003 by a team of archaeologists from the Museum of Archaeology of Catalonia – Empúries and the Institute of Cultural Heritage of the University of Girona.7 Most of the corpses had been wrapped in a shroud, which kept the skeletal elements in situ while the soft tissue decomposed in a protected space.
The skeleton studied was that of a very robust adult male. It was possible to reconstruct the skull and obtain biometric measurements. In general, the neurocranium was well preserved, with some areas of deterioration due to taphonomic processes, although nothing remained of the face except the mandible. The cranial sutures were not visible as there was total synostosis. An isolated styloid process was preserved. The post-cranial skeleton showed irregular conservation of the long bones of the extremities, and pelvic and thoracic elements, which were fractured due to the length of time spent in the deposit. There was slight osteophytosis on the surface of the ischial tuberosity and at the edge of the acetabular cavity of the hips. The vertebrae also showed some degeneration at the tip of the odontoid process of the axis, and along the edges of the intervertebral facets of the atlas. There were also alterations to the thoracic vertebrae, either in the form of Schmörl's nodes on the surface or osteophytic processes at the edges of the body and joint facets, while the lumbar vertebrae were damaged by osteophytosis and mild osteoporosis. Finally, some of the sternal ends of the ribs, which revealed calcification of the ligaments, corroborated the initial hypothesis of adulthood.8
The morphometric characteristics of the mandible were consistent with the aspects described above in terms of the age and sex of the individual (Figure 3). It was relatively well preserved, except for the upper third of the left ascending ramus, where the condyle and coronoid process were missing, having been lost posthumously. Only teeth numbers 37 and 38 were preserved in situ, and these showed considerable wear (particularly on number 37) as well as moderate loss of periodontal support. The state of conservation of the alveoli corresponding to teeth numbers 33, 32, 31, 41, 42 and 43 revealed that these were lost posthumously. The state of the alveoli of molars 47 and 48, in the process of osseous remodelling, suggested they may have been lost shortly before the individual's death. Teeth numbers 34, 35 and 36 must have been lost some time before death as the osseous remodelling of their respective alveoli was complete.9
The alveolus of tooth 43, partially preserved, showed an inclination that suggested displacement toward the vestibular side of the tooth root, as compared with that of number 33. The alveoli corresponding to teeth numbers 44, 45 and 46 were not clearly identifiable. The reason for this lack of information was a large, oval-shaped bone defect. While a definitive diagnosis of the lesion cannot be made because of a lack of soft tissue, it is consistent with a keratocyst. This extended from the apical region of the alveolus of tooth 42 (in its most mesial part) to the distal vestibular area of the alveolus of tooth 47 (in its most distal part) and had a maximum diameter of 45 mm. From the alveolar bone ridge to the mandibular inferior cortical bone the maximum diameter was 30 mm. The "window" appearance suggests that the lesion must have progressed as far as the periosteum through which, in all likelihood, it was in contact with the surrounding gingival soft tissue. Presumably the mandibular canal was dislocated downwards. Although the mandible studied was relatively well preserved, it was not possible to determine whether the lesion was unilocular or multilocular (if there were septa inside the cystic cavity) (Figure 4).
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Figure 4 Radiological appearance of the mandible studied, the projection being centred on the cystic lesion
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Final considerations
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Even today, keratocysts are not diagnosed frequently, and we have found no case reports in the literature that are compatible with such a diagnosis in antiquity. Hence, we believed it worthwhile presenting this case in which the pathological potential of this kind of odontogenic cyst can be clearly and directly observed.
Paleopathology is a discipline that has provided sporadic data, initially rather anecdotal in nature, dating back at least to the anatomists of the 16th century. However, it did not become a recognized scientific field until the mid-19th century when contributions were made by renowned figures such as the French archaeologist Jacques Boucher de Crèvecoeur de Perthes (1788–1868) and the German physician Rudolf Virchow (1821–1902).10 In the Spanish context, particular mention should be made of the neurosurgeon and paleopathologist Domènec Campillo, the prolific author of various works including La enfermedad en la prehistoria (Disease in Prehistoric Times).11
As the present study illustrates, this science, which is now gaining importance, has an interdisciplinary nature and draws on the combined knowledge of biological anthropology, archaeology, forensic medicine and geology, among other disciplines; this is illustrated by publications such as that of Isidro and Malgosa.9 Odontology plays a key role in the study of ancient remains, since it is the remains of the cranial skeleton, and especially the teeth, which best resist the passage of time following the individual's death. This is why studies of ancient remains are increasingly appearing in publications aimed at odontologists, radiologists and maxillofacial surgeons,5,12 providing selective data whose interest extends beyond these disciplines.
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References
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- Barreto DC, Chimenos E. New considerations about the diagnosis of odontogenic keratocyst. Medicina Oral 2001; 6: 350–357.
- Sapp JP, Eversole LR, Wysocki GP. Patología oral y maxilofacial contemporánea, (2nd edition). Madrid: Elsevier-Mosby. 2005: pp. 54–56.
- White SC, Pharoah MJ. Radiología oral. Principios e interpretación, (4th edition). Madrid: Elsevier-Mosby; 2002: pp. 364–367.
- Wood NK, Goaz PW. Solitary cystlike radiolucencies not necessarily contacting teeth. In: Wood NK, Goaz PW, (editors). Differential diagnosis of oral lesions (4th edn). St. Louis, MO, Mosby; 1991: pp. 375–405.
- Chimenos-Küstner E, Pérez-Pérez A, Agustí B. Evidence of hyperparathyroidism in a prehistoric mandible. Medicina Oral 1999; 4: 416–421.
- Blanas N, Freund B, Schwartz M, Furst IM. Systematic review of the treatment and prognosis of the odontogenic keratocyst. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000; 90: 553–558.[Medline]
- Aquilué X, Castanyer P, Santos M, Tremoleda J, Nolla JM, Sagrera J, et al. Les esglésies de Santa Margarida i Santa Magdalena. Setenes Jornades d'Arqueologia de les comarques de Girona, La Bisbal d'Empordà, 2004: pp. 274–295.
- Agustí-Farjas B. Estudi antropològic de la necrópolis de Santa Magdalena d'Empúries, 2004, unpublished study.
- Chimenos Küstner E. Perspectiva odontoestomatológica en paleopatología. In: Isidro A, Malgosa A, (editors). Paleopatología. La enfermedad no escrita. Barcelona, Spain: Masson, 2003: pp. 151–162.
- Aufderheide AC, Rodríguez-Martín C. The Cambridge encyclopaedia of human paleopathology. Cambridge: Cambridge University Press, 1998.
- Campillo D. La enfermedad en la prehistoria. Introducción a la paleopatología. Barcelona, Spain: Salvat, 1983.
- Jordana X, García X, Palacios M, Chimenos E, Malgosa A. Bifid mandibular condyle: archaeological case report of a rare anomaly. Dentomaxillofac Radiol 2004; 33: 278–281.[Abstract/Free Full Text]
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Abstract
Introduction
