CONTROVERSIAS EN CIRUGÍA ORAL Y MAXILOFACIAL I

 

Keratocysts of the jaw: Resective surgery

Queratoquistes maxilares: cirugía resectiva

 

 

J. Acero Sanz

Cirujano Oral y Maxilofacial. Profesor Asociado Cirugía. Servicio de Cirugía Oral y Maxilofacial.
Hospital Universitario Gregorio Marañón, Madrid, España

Correspondence

 

 

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ABSTRACT

Odontogenic keratocysts (OKC) affecting the jawbones are clinical entities with typical histopathologic features. OKC are locally invasive showing a high frequency of relapse. Treatment of these cysts remains controversial. Therapeutic approaches are based on two concepts: Masupialization or excision of the lesion. The aim of this paper is to review the existing controversy regarding this topic, focusing especially on surgical excision as a therapeutic approach.
Although no clear therapeutic approach has been defined, marsupialization and enucleation have higher recurrence or persistence rates than other methods. Surgical excision of the keratocyst combined with the elimination of epithelial islands in the overlying mucosa, and treatment of the surrounding bone with curettage or chemical cauterization with Carnoy´s solution, offer better results. Radical excision including wide bone margins remains also controversial. This approach can be considered as a therapeutic alternative in aggressive cases.

Key words: Keratocysts; Jawbones; Surgical treatment.

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RESUMEN

Los queratoquistes de los maxilares constituyen una entidad propia con típicos hallazgos histopatológicos. Estos quistes son localmente agresivos y presentan una frecuente tendencia recidivante. El tratamiento de los mismos permanece siendo controvertido. Como conceptos terapéuticos se manejan la marsupialización y la resección del quiste. En el presente trabajo revisamos esta controversia, con especial atención al tratamiento resectivo en sus diferentes variantes.
Aunque no existe una alternativa terapéutica clara, la marsupialización y la simple enucleación se siguen de inaceptables tasas de recidiva o persistencia de la lesión. La resección del quiste unida a la exéresis del tejido mucoso suprayacente y al tratamiento del lecho óseo mediante curetaje quirúrgico o soluciones químicas como la de Carnoy, parece ofrecer mejores resultados en el tratamiento de los queratoquistes de los maxilares. El tratamiento radical es asimismo controvertido, pudiendo indicarse en casos muy agresivos.

Palabras clave: Queratoquistes; Maxilares; Tratamiento quirúrgico.

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Introduction

The concept of the odontogenic keratocyst, described by Phillipsen in 1956,¹ often leads to confusion with regard to its definition. It is currently considered an entity of its own with typical histological features that consist of a polystratified keratinising squamous epithelium with a surface of parakeratin 80-90% of the time and of orthokeratin the remainder, a basal cell layer of cuboid or columnar cells and a thin connective capsule (Fig. 1). There may be small peripheral satellite cysts. The keratocyst contains a clear liquid, and on occasions there will be keratin- filled lumen. These cysts are locally aggressive having a tendency for recurrence. Their histogenetic origin is not well known. Its etiology is probably related with the existence of epithelial remains in the dental lamina that undergo cystic degeneration. This would explain the appearance of keratocysts in dental areas of the mandible or maxilla as well as in lateral periodontal areas. The mechanism through which these cysts develop from epithelial remains is not known, although their existence in other areas may explain the appearance of multiple cysts in the same patients, in a synchronized or metacronic fashion.²

The incidence of keratocysts varies according to the different authors, and it may vary between 3.2 and 21.8 of the maxillary cyst total. This wide variation may be due to the use of different diagnostic criteria, as on occasions keratocysts are confused with primordial cysts.³ The diagnosis can be given at any age, although it is more common in the third and fourth decades of life. The mandible is affected in 65 to 83% of cases, especially in the posterior region.⁴ Clinically most cysts are asymptomatic although, as a result of the expansive growth, deformity may appear in the affected area. On growing, the cyst may perforate bone cortex and affect soft tissue with a certain frequency.4 Associated manifestations such as nerve compression may appear. Cases of particularly aggressive behavior have been described such as penetration of the skull base.⁵

Radiologically the image of the keratocyst is not specific. In approximately 55-60% of cases there is a unilocular image while in the remaining cases multilocular images may appear (Fig. 2). The differential diagnosis should include other lesions such as well-developed follicular cysts, ameloblastomas or myxomas.³ The presentation of keratocysts in a multiple form is not unusual. In cases of multiple keratocysts, the presence of basal cell nevus syndrome should be excluded (Fig. 3). Gorlin and Goltz first described this in 1960 basing it on a genetic alteration with autonomic dominant hereditary characteristics. It has characteristic symptoms6 that include among others:

• Keratocysts of the jaws that are frequently multiple.

• Dentition anomalies.

• Cranio-facial changes, such as fronto-parietal bulging and hypertelorism.

• Cutaneous anomalies: multiple basal cell carcinoma. Epithelial cysts.

• Central nervous system disturbance.

• Other bone anomalies: changes in vertebrae, short metacarpal bones

The diagnosis of keratocysts is based, in addition to the clinical symptoms and radiographic features, on a histopathologic study of the lesion. A biopsy should be previously indicated before any treatment if this is suspected, especially with large lesions.

 

Discussion

Keratocyst treatment.

The treatment for keratocysts affecting the jawbones is basically surgical, and the way this is currently focused therapeutically still remains controversial, with rates of recurrence varying between 27 and 62% of cases. Recurrence of these lesions is regularly diagnosed during the first five years, but later recurrences have been described, up to 10 year after primary treatment.^2,4 (Figure 4). There is a possible relationship between recurrence and the type of treatment used, although there are few studies available that provide reliable conclusions, as most of these are retrospective, there is no follow-up information, or the series are short.

In view of this problem, various therapeutic methods have been put forward that are based on two different surgical concepts: marsupialization or the excision of the cyst. In addition to surgical treatment, various adjuvant methods have been described such as cryotherapy with liquid nitrogen or the use of Carnoy’s solution. Marsupialization, discussed in another paper in this Controversy, was described by Partsch, and as a result in certain references it can appear as a Partsch-I operation, with Partsch-II referring to the excision of the cyst and its direct closure. MARSUPIALIZATION consists in the aperture of the cyst towards the overlying surface, generally in an oral direction and more unusually towards the maxillary sinus. The borders of this aperture are sutured to the mucosa. The aperture is maintained, and lavage of the cavity is carried out, and on occasions this is plugged for a time until the keratocyst is either reduced or it disappears. This concept is based on the decompression of the cyst, as its expansion is halted and, according to some authors this may facilitate regression, as has been proposed by Brondum and Jensen.^8-10 Marsupialization is followed by recurrence in a high percentage of cases that can vary between 10 and 21% of lesions,¹¹ sometimes dramatically, as a result of which it is not considered a reliable method. Currently it should be limited, according to authors such as Stoelinga, to large cysts in medically compromised patients. Long-term prospective studies are required for a definitive evaluation.² On many occasions marsupialization does not lead to the disappearance of the cyst, but to its reduction. One variant of the technique combines marsupialization with the excision of the cystic remains once the size of the cyst has been reduced. This signifies a failure in the marsupialization concept, but it can be useful for large keratocysts with little surrounding bone and if excision entails a high risk of fracture.

The other concept that is used for surgical treatment of keratocysts is excision surgery, that is to say surgical extirpation and primary repair. This therapeutic approach can includes different modalities:¹

• Enucleation.

• Enucleation and curettage.

• Marginal resection.

• Segmental resection.

ENUCLEATION or a simple resection of the cyst while not acting on the surrounding tissue, has a recurrence rate that is significantly greater than the other methods of treatment, up to 54%¹² although some authors have not found this difference. ⁴ Zhao et al¹³ studied a series of 484 patients affected by keratocysts of the jaws, which included a follow- up of 255 cases, and they found a recurrence rate of 17.79% in 163 patients treated by means of enucleation, a significantly higher rate than that found by these authors with other alternative therapies such as the combination of enucleation with the application of Carnoy’s solution (recurrence in 6.7% of cases) or a wider excision (0%), a technique that will be discussed further on. As mentioned in the introduction, the explanation behind the high rate of recurrence of keratocysts after treatment is not clear. In this respect the hypothesis has been put forward regarding the recurrence or neoformation of keratocysts as a result of the existence of microcysts around the principal cyst, the breaking of the fine capsule during the removal of the cyst, or some molecular-based factor. Some studies show a greater rate of recurrence of cysts that are rich in parakeratin than in the cysts with parakeratin, although the relationship between the histologic type of the cyst and its behavior is not clear.¹⁴ Bone perforation by the cyst that has developed does not appear to be associated with a greater rate of recurrence, although recurrence has been related with treated tooth-bearing areas. As a result of this, some authors recommend the extraction of the teeth that are by keratocysts.

Therefore, rational treatment for keratocysts should be aimed at their removal along with the elimination of any possible remaining cells in the surgical bed in view of the histogenetic factors mentioned or with the splitting of the capsule. To this end, CURETTAGE AND/OR DRILLING can be carried out in addition to simple excision of the cyst, together with the excision of the mucosal areas by the cyst that could hold epithelial remains. Most of these remains are to be found in the oral mucosa overlying the cyst, especially at the back of the mandible, and as result removing this mucosal area together with the cyst is important, and this should preferably be done as a single block.² Other alternatives proposed by various authors for the elimination of these epithelial remains include the use of a cauterizing agent with little penetration of the excision bed surface, such as CARNOY’S SOLUTION, composed of absolute alcohol (6 ml), chloroform (3 ml), acetic acid (1 ml) and ferric chloride (1 g). We do not have any experience with this agent, which has lower reported recurrence rates than simple enucleation. ^2,13 The use of deep CRYOTHERAPY with liquid nitrogen does not seem appropriate as this is a more complex and potentially damaging method to underlying tissue such as the inferior dental nerve.² In cases of large multilocular cysts it is very important to treat all the cavities, eliminating the different bone septum (Figs. 5A and B). The inferior dental and lingual nerves should be identified and preserved if affected by a cyst. On occasions, there is no previous diagnosis in the case of small cysts that are excised simply as a result of another presumed diagnosis. If the postoperative histological findings are of a keratocyst, a close follow- up should be made.

RADICAL RESECTION is a more ample technique that includes in the extirpation of the cyst, an area of surrounding bone as a surgical margin, with the aim of eliminating all epithelial tissue existing as a satellite of the cyst in order to prevent recurrence. Depending on the size and location of the keratocyst, the excision can be marginal, so as to preserve the basal bone (Figs. 6A and B) or segmental, in the case of large cysts with little healthy bone margin that does not allow maxillary or mandibular bone continuity to be preserved. The segmental resection should be followed by the reconstruction of the defect according to the usual methods. Although a lower rate of recurrence has been described in cases of surgical resection as opposed to the other methods discussed (marsupialization, enucleation or enucleation with Carnoy’s solution),^12,13 segmental resection can be followed by recurrence, and it has even been described in a bone graft itself that was used for the repair of a defect.⁴ Radical resection is therefore controversial. Some authors consider that the presence of epithelial remains or microcysts is clear in mucosal areas overlying the cyst but debatable in bone margins, especially in the deeper ones, as a result of which there seems to be no clear need for carrying out radical bone resection, with it being more important to eliminate the overlying bone mucosa to which the cyst is joined, although in very advanced cases this type of bone excision may be necessary.² This concept would thus be valid for treating recurring keratocysts, in which the same concepts expressed for primary keratocysts should be used.

The more common complications in resective surgery of keratocysts of the jaws are infection of the surgical bed, damage to the inferior alveolar nerve in mandibular cysts, and the pathological fracture that Zhao reports in 2 cases in a series of 484 patients.¹³

 

Conclusions

The treatment for keratocysts continues being controversial. Marsupialization is a technique that entails discomfort for the patient and that can be followed by persistence of the lesion or recurrence, which frequently leads to the need for later excision. It can be indicated for patients with considerable disturbances to their general health, or for large lesions if reduction of their size before resective surgery has been considered. Simple enucleation has a high rate of recurrence, and as a result this technique is not justified on its own. Extirpation of the cyst together with the excision of the overlying mucosa related to it, and complementary treatment of the overlying bony bed by means of curettage or Carnoy’s solution, offers better results than isolated enucleation or marsupialization. Radical resection including bone margins is controversial, although there appears to be a high success rate, and it could be justified for aggressive lesions.

 

 

Correspondence:
Dr. Julio Acero Sanz
C/ Velazquez 27, 2º izda
28001 Madrid, España

Recibido: 25.07.2006
Aceptado: 31.07.2006

 

 

References

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