Introduction
There are a variety of cysts and tumors that affect the osseous marrow and cortex of the jaw bones, which may be uniquely derived from the tissues of developing teeth. It is important as an otolaryngologist to be aware of the variety of tumors and the presenting symptoms in these patients. A review of dental embryology is essential for further discussion of this topic.
Odontogenesis
In the earliest stage of tooth development, projections of dental lamina form invaginations into underlying ectomesenchyme. These cells differentiate into a layered cap with an inner and outer enamel epithelium, which contain inner stratum intermedium and stellate reticulum layers. Changes also occur in the underlying ectomesenchyme forming the dental follicle and dental papilla. Mesenchymally derived odontoblasts form along the dental papilla and secrete dentin, which induces the inner enamel epithelium to become ameloblasts. Ameloblasts are responsible for enamel production and eventual crown formation. Cementoblasts and fibroblasts from the dental follicle mesenchyme deposit cementum on the root surface and form the periodontal membrane, respectively. The penetration of these cells through Herwig’s sheath at the edge of the enamel organ give rise to epithelial rests of Malassez within the periodontal ligament. The enamel organ then involutes to a monolayer, which becomes squamoid and ultimately fuses with the gingiva during eruption.
Diagnosis of Odontogenic Cysts and Tumors
The most important concept in the management of odontogenic Questions about pain, loose teeth, recent occlusal problems, delayed tooth eruption, swellings, dysthesias or intraoral bleeding may be associated with odontogenic tumors and/or cysts. In addition, parasthesias, trismus, and significant malocclusion may indicate a malignant process. The onset and course of the growth rate of a mass should be elicited. pathology is obtaining a complete history and thorough physical examination.
The general head and neck examination should include careful inspection, palpation, percussion and auscultation of the affected part of the jaw and overlying dentition. Auscultation of the affected part of the jaw, as well as the common carotid and bifurcation may identify the bruit of a vascular malformation or tumor. Radiologic examination is usually the first procedure of choice in the evaluation of jaw related cyst and tumors. A panorex radiograph will often confirm clinical suspicions and have implications as to differential diagnoses. There are a variety of dental radiographic views that are routinely obtained during a dentist office visit that may incidentally discover occult cysts or tumors. In general, well-demarcated lesions outlined by sclerotic borders suggest benign growth, while aggressive lesions tend to be ill-defined lytic lesions with possible root resorption. With larger more aggressive lesions, computerized tomography may more clearly identify bony erosion and/or invasion into adjacent soft tissues.
A differential diagnosis is developed and tissue is then obtained for histologic identification of the lesion. Fine needle aspiration is excellent for ruling out vascular lesions prior to open biopsy and may be helpful to diagnose inflammatory or secondarily infected lesions. Open biopsy may be incisional (preferred especially for larger lesions prior to definitive therapy) or excisional (for smaller cysts and unilocular tumors).
Odontogenic Cysts
All true odontogenic cysts are characterized by epithelium lining a collagenous cyst wall. They are believed to arise from proliferation of normally quiescent epithelium in the jaw ( i.e., gingival rests of Serres, rests of Malassez) Cysts can be divided into inflammatory and developmental categories.
Inflammatory Cysts
Radicular (periapical) Cyst
This is the most common odontogenic cyst (65%) and is thought to arise from the epithelial cell rests of Malassez in response to inflammation. In fact, practically all radicular cysts originate in preexisting periapical granulomas. Radiographic findings consist of a pulpless, nonvital tooth that has a small well-defined periapical radiolucency at its apex are diagnostic. Large cysts may involve a complete quadrant with some of the teeth occasionally mobile and some of the pulps nonvital. Root resorption may be seen. The cyst is painless when sterile and painful when infected. Microscopically, the cyst is described with a connective tissue wall that may vary in thickness, a stratified squamous epithelium lining, and foci of chronic inflammatory cells within the lumen. Treatment is extraction of the affected tooth and its periapical soft tissue or root canal if the tooth can be preserved
Paradental Cyst
An inflammatory cyst forming most often along the distal or buccal root surface of partially impacted mandibular third molars, this cyst is thought to be the result of inflammation of the gingiva overlying a partly erupted third molar. Radiographically, it presents as a radiolucency in the apical portion of the root and represents from 0.5% to 4% of all odontogenic cysts. Treatment is by enucleation
Developmental Cysts
Dentigerous (follicular) Cyst
This is the most common developmental cyst (24%) and is thought to originate via the accumulation of fluid between reduced enamel epithelium and a completed tooth crown. It is usually found in the mandibular third molars, maxillary canines, and maxillary third molars. These cysts are most prevalent in the second to fourth decades. Radiographically, a unilocular radiolucency with well defined sclerotic margins encircling the crown of an unerrupted tooth is seen. Most cysts are asymptomatic, but large lesions can cause displacement or resorption of adjacent teeth and pain. Histologically, a cyst composed of thin connective tissue walls lined by stratified non-keratinizing squamous epithelium over a fibrocollagenous cyst wall. Treatment is with enucleation or decompression followed by enucleation if large
Developmental Lateral Periodontal Cyst
This cyst may arise from epithelial rests in the periodontal ligament or may represent a primordial cyst originating from a supernumerary tooth bud. It is most frequently encountered in the mandibular premolar region in adult men over 40 years. On radiographs, this cyst is an interradicular radiolucency with well-defined or corticated margins The adjacent teeth usually show some degree of root divergence and are vital. Microscopically, the cyst lining is either nonkeratinizing stratified squamous or stratified cuboidal epithelium with a minimally inflamed fibrous wall. The treatment is surgical enucleation or curettage with preservation of adjoining teeth
Odontogenic Keratocyst OKC
This is a specific and microscopically distinct form of odontogenic cyst that may assume the character of any of the odontogenic cysts. OKC comprises approximately 11% of all cysts of the jaws and are most often seen in the mandibular ramus and angle. It may be associated with the crown of a tooth appearing as a dentigerous cyst or may represent a keratinizing variant of the lateral periodontal cyst. Radiographically, it can mimic any of the jaw cysts and may appear as a well-marginated inter-radicular radiolucency, a pericoronal radiolucency or a multilocular radiolucency. When multiple keratocysts of the jaws are observed, the nevoid basal cell carcinoma syndrome should be investigated. The histologic features of OKCs include a thin epithelial lining with underlying connective tissue composed of a thin collagen layer with islands of epithelium that may represent other early cysts. Secondary inflammation may mask these characteristic features of OKC, resulting in misdiagnosis of a dentigerous, lateral periodontal, paradental or other more benignly behaving cyst. The most problematic clinical aspect of the OKC is the high frequency of recurrence, up to 62% in some studies, most recurring within the first 5 years of treatment. The thin and friable lining of the cyst wall often makes complete removal with enucleation difficult. Also, satellite cysts within the fibrous cyst wall may lead to recurrence if incompletely removed. Treatment often depends on the extent of the initial lesion. Small OKCs may be treated with simple enucleation if the entire cyst lining can be removed. Association with an impacted tooth requires removal of the cyst and tooth. A number of authors advocate removal of overlying soft tissues, which may contain remnant epithelial elements, in an attempt to decrease recurrences. The most common current method is total enucleation with or without a “peripheral ostectomy” to carefully excise the entire specimen. A recent study by Bataineh, et al., promotes complete resection without continuity defects through an intraoral approach. They advocate resection of cortex bone approximately 1 cm around the lesion with sacrifice of any teeth incontinuity with the lesion. When perforation of the cortex occurred, the overlying mucosa/soft tissues were also excised. The osseous walls of the defect were abraded with course surgical burs and the defect was packed with Whitehead’s varnish on Iodoform gauze for 5 to 8 days. The inferior alveolar nerve was free of pathologic tissue and spared in all cases. No reported recurrences with a follow up from 2 to 8 years were found with this method. Long term follow-up with periodic x-ray is recommended, as OKCs have been known to recur 20 to 40 years after initial treatment
Glandular Odontogenic Cyst GOC
This is one of the more recently described odontogenic cysts. It is uncommon, originally described in 1988 by Gardner, et al.. Most have been reported to occur in the mandible (87%), particularly the anterior region (90%). The age range is from 14 to 90 years, with a mean of 49.5 years. Swelling is the most common complaint with pain about 40% of the time. These cysts tend to have a very slow progressive growth. Radiographically, they can present as either unilocular or multilocular radiolucencies. Its histology shows a stratified epithelium with cuboidal, sometimes ciliated, surface lining cells. There is a polycystic nature to the lesion with both secretory elements and stratified squamous epithelium, often with epithelial spheres, plaques, or plaque-like thickenings. There is considerable overlap between the histologic features of the GOC and central low-grade mucoepidermoid carcinoma. This cyst has a considerable recurrence potential, about 25% after either enucleation or curettage, so some have suggested marginal resection. Curettage or enucleation can still be effective, provided the clinician follows the patient closely for several years, and the lesion does not involve the posterior maxilla.
Nonodontogenic Cysts
Incisive Canal Cyst
This is a developmental nonodontogenic cyst derived from embryonic epithelial remnants of the nasopalatine duct or incisive canal. It typically occurs in adults (4th to 6th decades) with no sex predilection. It is a well-delineated oval or heart-shaped radiolucency located between and apical to the two maxillary central incisors in the midline. Palatal swelling is common, and occasionally, the incisors will show evidence of root resorption. The cyst is asymptomatic and is usually an incidental finding on routine dental radiographs. Histologically, the cyst may be lined by stratified squamous epithelium, respiratory epithelium, or both. Treatment may consist of surgical enucleation or periodic radiographic follow-up. Progressive enlargement warrants surgical intervention
Stafne Bone Cyst
The Stafne (static) bone cyst or submandibular salivary gland depression is usually discovered incidentally on dental radiographs, It is asymptomatic and is not a true cyst, rather an anatomic depression in the lingual aspect of the body of the mandible where normal salivary gland tissue rests. The radiographs show a small, circular, corticated radiolucency below the level of the mandibular canal. Histologically, normal salivary tissue is found and no treatment is required except routine radiographic follow-up
Traumatic Bone Cyst
The traumatic cyst is not a true epithelial cyst, but represents an empty or fluid-filled cavity of bone lined with a fibrous or granulation tissue membrane. The term traumatic was used to implicate trauma as the cause. However, less than half of the instances are associated with any significant trauma to the jaw with an unknown etiology. The lesion is located most often in the body or anterior portion of the mandible, and radiographically it is radiolucent. A classic feature is its tendency to scallop between the tooth roots. The overlying teeth are vital. Microscopically, a thin membrane of fibrous granulation tissue may line the cavity. Treatment with exploratory surgery following aspiration causes hemorrhage which may expedite healing
Surgical Ciliated Cyst of Maxilla
Following a Caldwell-Luc operation, fragments of sinus epithelial lining may become entrapped in the surgical site. If this epithelium undergoes benign cystic proliferation, a unilocular well-delineated radiolucency will become evident in the maxilla. The lesion lies within the alveolar bone subjacent to the antral floor and is generally confined to an edentulous or inter-radicular area in the posterior maxilla. Pain or discomfort may be present. Histologically, the cyst is lined by pseudostratified columnar ciliated epithelium with an inflammatory connective tissue wall. Treatment is with surgical enucleation
