IN THIS PAGE
DIAGNOSIS OF CYST OF ORAL AND MAXILLOFACIAL REGION
- Clinical Examination
- Aspiration Biopsy
- Radiographic examination
TREATMENT OF CYSTS "BASIC SURGICAL TECHNIQUES"
- Standard Teqniche
- Mursupilization with complete removal of the cyst lining
- Enucleation with primary closure
- Enucleation with the use of cavity obliterating materials
- Secondary enucleation and wound closure
TREATMENT OF CYSTS "CLINICAL APPLICATIONS"
- Odontogenic Keratocyst
- Non-odntogenic cysts
- Bone cysts
- Nerve Involment
- Obliteration of Maxillary Sinus
- Facial or Cervical Sinuses
- Carcinoma Arising in the Cyst Lining
- Fracture of the Mandible
Cyst Lectures and Figures
DIAGNOSIS OF CYST OF ORAL AND MAXILLOFACIAL REGION
A. Signs And Symptoms
1. Bony Expansion
Small cysts usually presents no expansion. Nowever, as the cyst increase in size expansion of the alveolar plate occurs. In cases of odontogenic cysts usually the labial or the buccal plate of the lower jaw is expanded. Expansion of the lingual plate may be an indicative for another lesion.
The sequence of events of cyst expansion shown in figure 1 is usually observed in cases of inflammatory and dentigerous cysts. Odontogenic keratocyst, on the other hand, tends to cause little expansion that may be overlooked. Soliatory bone cyst usually produce expansion late in its course.
Fluctuatioin occurs when the bone overlaying the cyst become resorped due to increased cystic pressure and the cyst lining comes in contact with the oral mucosa. The sensation of fluctuation can be convyed via the cystic fluid. Fluctuation can be demonestrated by applying a firm interrupted pressure with the fingre of one hand over the lesion and detecting the transmitted wave with the fingure of the other hand placed onthe opposite side oft he lesion.
Fig. 1. Sequence of cyst expansion.
Although periodontal and dentegerous cysts may occur any where in the jaws yet ther is some site predlecation for certain types of cysts. (Table 1)
4. Teeth related to the cyst
Benign cysts rarely cause loosening to the adjacent teeth until the cyst attain very large size. If the cyst develope between two teeth it usually cause the roots to diverge and the crowns to converge. Large cysts in the maxill frequentelly displace the roots of the adjacent teeth buccaly so that the crowns of the teeth are inclined palatally. Table 2 shows a list for some creteria of adjoining teeth.
5. Paraesthesia of the inferior dental nerve
Although large mandibular cysts usually involve the neurvascular bundle, and may even deflect it to an abnormal position, paraesthesia of the nerve distribuation is very rare. Nerve paraesthesia usually occurs when the cyst becomes infected and the accumulation of the inflammatory exudate results in sudden increase in the intercystic pressure. This result in neuroperxia of the nerve and immediate onset of lower lip paraesthesia.
1. Pain and swelling
Small cysts are usually symptomless, the frist symptom is usually pain and swelling when the cyst becomes infected or attain large size.
2. Bad taste
If an infeted cyst discharge pus into the mouth the patient may complain of a nasty taste. On the other hand, if the cyst attain large size and presents a sinus discharging cystic fluid the patient complain of a salty taste.
3. Irrigularitis in dentition
As the syst may cause displacement of the adjacent teeth the patient may complain of irrigularitis in dentition that was not present. Thew patient may also complain of discloration of a nonvital tooth associated with a periapical cyst.
4. Pathological fracture
When the cyst attain a large size it may cause pathological fracture in the weakened mandible. It is surprisingly how few symptom a pathological fracture may cause. Sometimes only a click followed by mild discomfort and progressive but slight disturbances in occlusion are all the symptoms of a pathological fracture.
5. Edentulous patients.
In edentulous patients cysts may cause discomfort of a previously well fitting denture, which may be dislodged by an expanding cyst. At the area where the denture flange cut into the growing lesion a denture granuloma may develop.
Aspiration of a suspected cyst is a very useful diagnostic aid, especially when doubt still exist about the nature of the lesion after clinical and radiographic examinations.
A wide pore needlw should be used. It is inserted in the suspected cystic lesion under local anaesthesia and the cavityu is aspirated. A provisional diagnosis of benign cyst will be confirmed if the aspirated fluid is a ligth straw-colored fluid containing cholestrol crystals. The presence of the cholestrol crystals can be easily demonestrated by running some of the aspirated fluid onto a dry swab glass. The smear is then viewed under strong light micrscope where the cholestrole crystals can be identified by their distinctive shape "Rectangular with one corner missing". Table 3 Shows defferntial diagnosis of aspiration biopsy.
Radiography is an essential diagnostic aid in diagnosis of cystic lesions. Intraoral periapical films usually demenstrate small cysts. In case of large cysts only part of the cystic lesion will be seen in the film (Figs 1-2 and 1-3). This is due to the small size of the film. Intraoral occlusal films, on the other hand, are very useful in cases of maxillary lesions to show the amount of palatal bone destruction (Fig. 1-4). In the mandible occlusal films the degree of expansion of the outer and inner cortical plates (Fig. 1-5).
Extraoral radiographs (Table 1-4) generally demonestrate the extent of the cystic lesion, the displacement of the adjacent teeth and the encroachment of the lesion uppon vital important structures as the maxillary sinus, the inferior border of the mandible or the orbiatal cavity. (Fig. 1-6)
Fig, 2. Aspiration biopsy.
The use of radio-opaque medium
Radio-opaque materials, as lipedol, may be injected into the cystic lesion to aid in the explortion of the extent of the cystic cavity (Fig. 1-7). Indications for the use of radio-opaque medium and the technique used are both shown in table 1-5.
Fig. 3. The use of radio-opaque media to demonstrate the extent and relation of the cyst. The extent of the cyst can be determined. A cyst within the maxillary sinus can be clearly demonstrated
1. Shape of the lesion
Small cysts in cancellous bone are round, as they expand their circular shape tends to be lost. This is attributed to the defference in the degree of resistance of the bone surrounding the lesion. When a mandibular cyst comes in contact with the cortical plates it tends to expand along the longitudinal axis on the expense of the less solid cancellous bone.
2. Perforation of the cortical plates
When either or both mandibular corticxal plates are perforated the resultant hole is evedinced by a well demarcated dark shadow. When the images of perforations of both cortical plates partly overlap, a complex image of false multilocularity is produced.
3. Relation to the mandibular canal
The presence of a large cyst in the mandible may cause downward displacement of the mandibular canal with discontinuing of one or both of the cortical lines which outline the canal. The inferior dental bundle may come to lie within the cystic capsule.
4. Maxillary cysts
Maxillary cysts are usually discovered when they attain alarge size, yet there may be no clinical expansion.
5. The presence of unerupted tooth
The presence of an unerupted tooth in relation to a radioleucent area is not necessary diafgnostic for dentigerous cyst. The tooth may be associated with a neoplasm or another type of cyst the enlagrgement of which enclose the tooth at an early stage.
Multilocularity is usually false in true bvenign cystic lesions being a projection effect of the bony elecations or ridges in the bony walls of the cyst which result from uneven bone resorption. Also false multilocularity may result from partial superimposition of resorption defects in the buccal and the lingual cortical plates.
7. Palatal cysts
Palatal cysts usually do not cross the midline line. This may be attributed to the restraining effect of the median suture of the hard palate which closes late about the 5th decade of life.
8. Radiographic defferntiation between maxillary sinus and maxillary cyst
- The antrum has certain anatomical structures while the cyst is structureless.
- The maxillary sinus are symmetrical and onther cavity will be found on the other side.
- Teeth projecting into the cavity retain an intact lamina propria when related to the maxillary sinus.
9. Radiographic defferntiation of mucous cyst
- Relatively radioopaque shadow in relation to the dark shadow of the air filled cavity of the sinus.
- The lesion is devoid of white border on its free upper surface.
- Usually no displacement or resorption of the antral floor which is possible with odontogenic cysts.
- The maxilary teeth in relation to the cyst has an intact lamina propria.
- The cyst may arise from any wall of the sinus and not confined to the floor.
TREATMENT OF CYSTS "BASIC SURGICAL TECHNIQUES"
Regardless of the type of the cyst surgical treatment of oral cysts is basically either one of three procedures. These are mursupilization, enucleation and mursupilization follwed few weeks later by enucleation, i.e. combination of both procedures. Treatment of oral cysts should have the following five objectives:
- Aim to remove the lining or to enable the body to rearange the position of the abnormal tissues so that it is eliminated from the jaw.
- Restoration of the affected part to normal or nearly normal form and normal function.
- Preservation of the adjacent teeth and other important structure as the inferior dental canal and the maxillary sinus.
- Minimal trauma to the surrounding tissue.
- Rapid healing after removal of the pathological tissues.
Mursupilization is the process of cyst decompression which is made possible by deroofing of the lesion. The surrounding mucoperiosteum is sutured to the cyst lining or held in place with packing. The cyst is made as an accessory compartment of the oral cavity. Indications, advantages and disadvantages of mursupilizatin are listed in table 2-1. Figure 2 shows diagrammatic scheme for the healing process of the cystic lesion following mursupilization.
Fig. 2.Mechanism of healing after cyst decompression.
I. Standard Technique
• Incision and flap reflection: A U-shaped flap is performed. The flap is placed within the bounderies of the cyst with the base of the flap toward the sulcus. During flap reflection care should be taken to avoid perforation of the cyst lining with the periosteal elevators in areas where bone is resorped and the cyst lining comes in contacct with the mucous membrane. Palatal and lingual approach for marsubialization should be avided as palatal defects will affect speach and lingual defects will be deffecult to be cleaned.
• Bone removal: Bone, if present, is removed using burs, chisels and rongures to create a window in the labial or buccal plate. The bony opening should be as large as possible to avoid the rapid contracture of the tissues and closing of the apprature. In edenulous areas the crest of the ridge should be preserved as a foundation for future denture construction.
• Cutting the cyst lining: The exposed cyst lining is then cut away flush with the edge of the bony window. This is done using siccors or scalpels. The scalpel is stapped therough the cyst lining and the cutting is done from within outside aganist the bony edges.
• Suturing the flap to the cyst lining: The flap is then folded into the cavity and sutured to the cyst lining. The cavity may be packed with ribbon gauze impregenated in white head varnish or simillar materials. The pack is changed evry 48 haours for 7-10 days until healing occurs between the cyst lining and the mucosa. This pack has the following advantages:
- Prevent the cavity contamination with food at the immediate postoperative period.
- Cover any raw bone or wound edges.
- Allow union between the cyst lining and the overlaying mucosal flap.
• Construction of a cyst plug: Construction of the cyst plug is indicated when the bony opening is small in relation to the size of the cyst, either due to anatomical reasons or the need to avoid damage to the adjacent teeth. Also it is indicated when the the bony opeining is placed entirely or partially in areas covered with sulcus mucosa that is supported with loss connective tissue. Slcus mucosa tends to contracts and reduces the size of the opening to 1/4 its original size within few days unless the opening is mechanically maintained. Requirements of the cyst plug are shown in table7.
Modification of the standard teqniche:
• Archer’s Modefication: When the bucal plate of bone over the cyst is resorped over a considrable area and the cyst lining is adherent to the over laying mucosa. The cyst lining and the buccal mucosa are sutured together by taking 4-6 sutures at the limits of the bony defects. Incision is then made for both the cyst lining and the mucosa, at the level of the sutures, cutting a large window into the cyst. The cavity is then filled with gauze which is then removed after 7 days.
• Triphination or tube drainage (Thoma’s modification): This method is used when the cavity of the cyst is large and involve vital teeth or important structures. A small opening is made into the cyst through which a small metal or polyethelene tube is inserted into the cystic cavity and ligated to the soft tissues. This will relieve pressure from inside the cyst and allow gradual obliteration of the cavity. Periodic irrigation of the cavity should be performed through the tube which may be shortened as the cavity is obliterated.
II. Marsubialization with complete removal of the cyst lining
When the bony opening is completed the entire cyst lining is removed. The mucosal flap is then trimmed to allow it to be folded into the cystic cavity to cover part of the bare bone. The rest of the bone is covered with a periodontal pack or the cavity is packed with ribbon gauze. The pack is left for 7 days until the bare bone becomes covered with granulation tissue. This technique allow more rapid filling of the defect with bone.
Enucleation is the complete removal of the cyst lining after which the bony defect is either primary closed or packed open. Advantages, disadvantages, indications and contraindica-tions of enucleation are listed in table 8.
I. Enucleation with primary closure
• Incision: An incision that fulfill the requirements of the ideal flap is performed and the flap is reflected gentely taking care not to perforate the cyst lining in areas where their is resorption resorption of the cortical plate. Approach is usually labially or buccally. Palatal approach is indicated when the cyst enlarges palatally. However, when the teeth are to be root canal filled and apecectomized palatal approach is contraindicated.
• Teeth extraction: If a tooth or more are involved in the cystic lesion and are to be extracted, this should be done before bone removal. Otherwise, the weakened alveolar bone may be fractured during extraction.
• Bone removal: After reflection of the mucoperiosteal flap, if the overlaying bone is intact, a window is made through the cortical plate using burs and/or chisels. The opening is then enlarged using ronguers. It is useful technically to separte the cyst lining for some distance from the edges of the bony window before using ronguers. When the overlaying bone is thin and fragmented the small pieces of bone are peeled off the underlying cyst lining.
• Removal of the cyst lining: It is preferable to start enucleation of the cyst lining at its junction to the edges of the bony opening. Enucleation is performed using curettes. Some authers prefere not to puncture the cyst lining before the enuccleation as it is easier to be defined and removed. On the other hand, other authers prefere to puncture the lining and evacuate its content to allow the lesion to collapse to facillitate its removal through a small bony opening. Some technical points that should be remembered during enucleation of the cyst lining are listed in table 9.
• Wound inspection and clousre: After removal of the cyst lining the cavity is irrigated, deried and inspected for the presence of any remenants from the lining or any denuded tooth apices which, if present, the tooth should be either extracted or root canal filled. The edges of the bone are then smoothed using bone filles and the flap is repositioned and sutured.
II. Enucleation with the use of cavity obliterating mateials
When the cystic cavity is large in size the resultant large dead space that is filled with blood clot may lead to liquefication and breakdown of the blood clot. This is more liable to occur in the mandible than in the maxilla. To overcome this possible complication the cavity is either completely or partially filled with a space obliterating material. Material in common use nowadays are bioglass, calcium hydroxide and bone cements. Different types of bone grafts may also be used as aspace obliterating material. Advantages of the use of cavity obliterating materials and the requirements for its sucessful use are listed in table 10.
III. Secondary enucleation and wound closure
This procedure is a combination between marsubialization and enucleation. The cyst is decompressed first and once sufficient bone has been formed to cover and protect the particuylar structure at risk. Once the cyst has been decompressed the lining well be thickened and made stiff by increases layers of fibrous tissues and becomes more easily enucleated. The lining may be enucleated and a flap is raised to cover the defect.
It is essential to prepare a flap to cover the defect. This is usually performed by lateral displacement of the flap from one side rather than by an atempt to advance the sulcus or cheek mucosa. Also the flap should be large enough to cover the margins of the defect. Before suturing the edges of the defect must be refreshed.
TREATMENT OF CYSTS "CLINICAL APPLICATIONS"
The term keratocyst is based upon the histological apperance of the cyst lining. The histological creteria of keratocysts are listed in table 11. Keratocysts has a high recurrecnce rate (60%). The possible causes of the recurrence tendency of keratocysts are:
- The lining is thin and friable and it easily tears during operation and left behind in the osseous wall of the bony cavity.
- The cyst frequentely penetrate the cortex and the liing becomes adherent to the mucosa. Separation of the lining from the mucosa is difficult and may result in seeding of some cells from the lining into the surrounding tissus.
- The presence of microcysts in the wall of the cyst.
- The presence of strands or rests of odontogenic epithelium, some of which are in direct contact with the basal cell layer of the oral mucosa "Dropping-off Phenomena". For this reason some surgeons advise the removal of the overlying mucosa with the cyst lining.
• Unilocular keratocyst: When accessible it must be enucleated, if not accessible it is primraly decompressed and then enucleated.
• Unilocular with loculated periphery: Treatment is enucleattion with regular follow-up or, preferably, inblock resection.
• Multilocular keratocyst: Resection of the containing block of bone, i.e. block excesion, with immediate bone grafting.
NOTKERATINIZED ODONTOGENIC CYSTS
1. Eruption cyst
These are superficial cysts that has a smillar relation to the corwn of the tooth to the dentegerous cyst. They are most commonly seen over an erupting frist molar.Clinically eruption cyst is presented as a dark blue or purple tense swelling.The cyst never cause bone destruction. Spontenous rutpture followed by eruption of the tooth is common. However, if the episode is unusually prolonged a simple incision of the cyst is usually followed by relief of symptoms and eruption of the tooth.
2. Radicular cysts
Inflammatory periodontal cyst of odontogenic origin is the commonest of all types of cysts. It result from inflammatory hyperplasia of the epthelial rest of Malassez following death of the pulp. Inflammatory periodontal cysts are either "radicular" when related to the apex of the tooth or "lateral" if related to an accessory root canal. "Residual cysts", on the other hand, are radicular or lateral periodontal cysts that have been left behind after of the related tooth at some previous time.
• Enucleation: Enucleation of radicular cysts and lateral periodontal cysts is the most common treatment. As several adjoining teeth roots may be protrouded into the cystic cavity vitality testing of these teeth is essential to exclude those which are sound. When there is a sinus track it must be excised.
• Marsubialization: Due to its disadvantages it is advocated only when the cyst is very large or enchroch upon important structure or when the general condition of the patient limits the extent of surgery.
What ever the chosen line of treatment radiographic follow-up is essential to confirm that a steady bone regeneration is taking place. Follow-up should be continued until complete healing occur. For well known reasons large number of films should not be taken at frequent intervals. Two to three films are taken at 3 months interval and then at 6 months interval or annually.
3. Dentigerous cysts
Denntigerous cyst usually originates through alteration in the reduced enamel epithelium of the tooth follicle after the crown of the tooth has been completely formed. Fluid accumulate between the enamel epithelium and the crown of the tooth.
The dentigerous cyst envelope the crown of the tooth. When it envelope the whole cown it is called central type and when the cyst is related tangenitally to the crown of the tooth it is called lateral type. A dentigerous cyst may also be found enclosing a complex compond odntom or a supenumeray tooth. The dentigerous cyst is the most agressive type of all odontogenic cysts. (Table 12)
• Marsubialazation: Marsubialization is a satisfacctory line of treatment in children. It is often followed by rapid bone formation and shrinkage of the cavity in size. This will reduce the risk of jaw fracture. Both the tooth of origin and any other tooth that may be prevented from eruption by the cyst will move upwords.
• Enucleation: Enucleation of dentigerous cyst is usually accompanied by removal of the tooth of origin. In children an attempt may be made to preserve the tooth of origin, however it is neccessary to separate the lining from the neck of the tooth using scalple. Even so, if part of the rot has been formed the chance of this tooth to erupt is very little.
4. Primordial cyst
Primordial cyst develops through cystic degeneration and liquification of the stellate reticulum in the enamel organ of a tooth or supernumary tooth before any calcified tissues has been laid down. Accordingly the primordial cyst takes place of a missing tooth unless it arisese from the follicle of a supernumary tooth.
Primordial cyst is the least common type of all odontogenic cysts. It usually seen in young adults. The lesion is usually painless unless secondary infected. Radiographically it appears as round or ovoid well demarcated radioleucent area which do not show constantly the sclerotic line of bony reaction.
Histologically the primordial cyst show some degree of keratinization. Occassionally keratin may be found to fill the cystic cavity. The subepithelial connective tissues may contain groups of epithelial cells at some little distance from the main epithelial lining of the cyst. These cells are of odontogenic orgin and represent remaenants of the dental lamina.
One striking feature of the primordial cyst is its tendency for recurrence. The recurrence rate varies from 10-60%. Various suggestions has been made to acount for this behaviour, these are:
- It is due to the relatively thin cyst lining which may result in leaving some remanants behind after enuccleation procedure.
- Doughter cysts are quite common to occur possibly because the adjacent areas of dental lamina undergo cystic changes or less likely because multicystic changes occurs in the enamel organ. Such doughter cysts may very easily be left behind after enucleation of the main cyst.
Accordingly, removal of this type of cysts must be done with careful enucleation and throuogh curettage to garde aganist possible recurrence.
1. Incisive canal cyst
Treatment of incisve canal cyst is usually enucleation of the lining with primary closure. An incision is made arround the gingival margins of the teeth or on the crest of the ridge in edentulous patients. The size of the flap is governed by the posterior extension of the cyst. After reflecction of the palatal flap it may be necessary to release the cyst lining from the overlying mucoperiosteum with a knief. Also sufficient bone removal should be performed to enable the upward extension of the cyst to be traced and removed. The lining is often adherent to the contents of the incisive canal. This connection may need division with knifes or scissors.
2. Palatine papilla cyst
It is better to be removed by excision of a small elipse of palatal mucosa circumscribing the lesion. The adjacent mucoperiosteum is rasied and the wound is sutured. If the edges of the wound can not be approximated a surgical pack is applied to the area which is left to heal with secondary intesion.
3. Nasolabial cyst
This is a soft tissue cyst which is treated by excision under either local or general anesthesia. An incision is made over the convexcity of the swelling in the buccal mucosal. The incision should not reach the periostium as the cyst lies extraperiosteally. The soft tissue is retraccted and dissected away from the cyst lining. Usually there is a firm adherence btween the lining and the surrounding soft tissues and sometimes to the mucosa of the nose. The lining is removed and the wound is closed and pressure pack is applied on the cheek for 24 hours to prevent hematoma formation.
1. Haemorrhagic (Traumatic) bone cyst
This cyst has an unknown etiology and very charateristic radiographic picture. It occurs usually in the mandibular molar region. The condition is generally painless and may be discovered by the patient only if there is swelling. However, expansion of the bone is uncommon. Radiographically the lesion has a well defined radiolucent area that have the very characteristic "Scalloped apperance" where it extends between the roots of the teeth.
Histologically the lesion composed of a space in the bone that contains a little clear or blood stained fluid. The cavity is lined with a very thin connective tissue membrane. There is no disectable cystic sac. When the cavity is posterior to the mental foramen the inferiodental bundle may be found freely exposed in the cavity of the cyst. This finding is diagnostic.
Surgical exploration of the area is essential to confirm the diagnosis and it also constitute the treatment. It was found that opening the lesion, evacuating its contents and reestablish bleeding result in rapid obliteration of the cavity by new bone.
2. Aneurysmal bone cyst
This type of cysts occurs mainly in long bones and verteberal columen. It may occurs in the mandible and less commonly in the maxilla. Jaw lesions usually affects young adults and there is usually a history of trauma. When the lesion is entered it is found to contain blood, riddish-brown connective tissues and further bleeding may occur from the walls of the cavity.
Radiographically the lesion appears as a unilocular or multilocular trancleucency that may show the characteristic excentrically blooned or hony comb apperance.
This type of cyst is treated with curettage or local excision. A troublesome beeding may be encountered during the operation. Radiotherapy may also be used when the lesion is inacessible for surgical excision, e.g. lesions in the vertebrae. Postoperative radiographs are essential to demonestrate the progress of bone regeneration. Recurrence of the lesion may occur following inadequate removal of the cyst and a second operation may be essential.
Nerve involvement with paraesthesia or anaesthesia of the lower lip is quite uncommon with uncomplicated mandibular odontogenic cysts. However, anaesthesia or paraesthesia of the lower lip may occur in the following cases:
- If malignancy developed in the wall of the cyst.
- If the cyst becomes infected.
- Postoperatively due to operative trauma during surgical removal of the cyst lining.
Full return of sensation to the affected region usually occurs within a short period of time after removal of the cyst.
On the other hand, maxillary cysts rarely cause any alteration in sensation in the upper lip or over the infraorbital region. However if either of these complication occured after surgical removal of the cyst recovery is irrigular but complete.
OBLITERATION OF MAXILLARY SINUS
When maxillary cyst gradually enlarge and encroach upon the maxillary sinus the antral bony floor becomes gradually attenuated and resorbed. The cyst comes in contact with the lining mucoperiosteum of the sinus and pulges into the air space until the whole sinus is occupied by the cystic lesion. Sometimes there may be distortion of the bony outline of the sinus and the lateral and/or the medial walls may undergo resorption. Treatment of the cyst is followed by restoration of the normal contour of the antral cavity.
FACIAL OR CERVICAL SINUSES
The development of external sinuses may occur when the cyst becomes infected. The sinus may be actively draining or may be chronic. The sinus has a contracted packered unsightly orifice. After tretment of the cyst the sinus usually disappear but unsightly ugly demple may remain at the original site which call for surgical correction. (Table 13)
CARCINOMA ARISING IN THE CYST LINING
It has been stated by many authers that true develpment of carcinoma in a cyst lining is uncommon but do occur. Other possible relations when undoubted squamous cell carcinoma is associated with a cyst are as follow:
- The initial lesion was the epithelium neoplasm and the cystic cavity resulted from breakdown of part of the growth.
- The neoplasm represent a metastatic deposite situated close to a simple cyst with the primary lesion situated elsewhere in the body.
- Carcinoma has arise in a cystic ameloblastoma.
- The cyst was not directely related to the tumor, both has arose separately in adjacent areas and become fused in some parts.
Carcinoma associated with cystic lesion is usually diagnosed as odontogenic cyst. The underlying malignancy remains unsuspeccted until surgical exposure and biopsy. This is attributed to the tendency of the tumor to grow into the cystic cavity. For the same reason the chance for cure is good if diagnosis and treatment were performed early. Signs and symptoms which should arose suspeicison to the presence of a neoplastic activity in a cystic lesion are listed in table 14.
The recommended line of treatment is wide surgical resection and in the lower jaw this may be hemimandibulectomy. As a rule any pathological cystic condition should be removed without delay and the lining should be carefully biopsed.
FRACTURE OF THE MANDIBLE
Large cystic lesion in the mandible may lead to pathological fracture as it weakened the bone. Fracture may occur on trivel trauma or even during sleep. Signs and symptoms of pathological fracture are very slight. These include slight pain, abnormal mobility, malocclusion and crepitus.
Treatment of fracture through a cystic lesion is challengable. However, there are certain broad principles of treatment which should be taken into consideration. These principles are discussed in the following pages.
1. The nature of the cystic lesion
A cystic cavity with no lining as traumatic bone cyst and Stafne’s bone cavity, can be ignored during treatmet of the fracture. For all other types of cysts the cyst capsule should be enucleated frist before reduction and immobilization of the fragments. The cyst lining is liable to secondary infection which result in delayed union or nonunion of the bony fragments. On the other hand, if malignant changes has occured in the cyst frist attention should be given to the treatment and mangament of the neoplasm.
2. Degree of destruction of the mandible
When the cyst is of moderate size and satisfactory contact can be established betwen the fragments to assure bone union, treatent is enuclation of the lining followed by reduction and immobilization of the fragments. On the other hand, if the cyst is large and no satisfactory contact between the fragments can be established, bone grafting should be considered.
Onther line of treatment of fracure associated with very large cysts is marsubialization together with immobilization of the mandible after reduction of the fragments. Elemination of the intercystic pressure will result in bone apposition under the cyst capsule. Healing of the fracture will occur as the cavity gradually decrease in size. A second operation can be performed after union of the fragments to remove the cyst lining.
3. The presence of infection
If the pathological fracture occured through an infected cystic cavity it is a must to irradicate the infection before treatment of the fracture.