BDS12029 Radiographic Interpretation of Cysts - Newgiza University PDF

BDS12029 Radiographic interpretation of cysts and cyst-like lesions of the jaws Aim: The aim of this lecture is to provide an overview of the radiographic features and interpretation of cysts and cyst-like lesions of the jaws. Objectives: By the end of this tutorial, the student should be able to...

BDS12029 Radiographic interpretation of cysts and cyst-like lesions of the jaws Aim: The aim of this lecture is to provide an overview of the radiographic features and interpretation of cysts and cyst-like lesions of the jaws. Objectives: By the end of this tutorial, the student should be able to: • Recognize the different cysts and cyst-like lesions of the jaws on radiographs • Identify the differences between them, radiographically • Interpret those lesions by accurately and systematically describing the radiographic findings Definition A cyst is a pathologic cavity filled with fluid, lined by epithelium, and surrounded by a definite connective tissue wall. General features of cysts Clinical features • Mostly found in the jaws (most cysts originate from the rests of odontogenic epithelium that remain after tooth formation). • Slowly growing swelling • Painless (unless secondarily infected or related to a nonvital tooth) • May be associated with unerupted teeth, especially third molars. General features of cysts Radiographic features 1. 2. 3. 4. 5. 6. Location Shape and periphery Internal structure Effect on surrounding structures Size Number 1. Location 2. Shape and periphery • May occur centrally (within bone) in any location in the maxilla or mandible (rare in the condyle and coronoid process). • Odontogenic cysts: - in the tooth-bearing region - mandible: originate above the inferior alveolar canal - maxilla: may grow towards the maxillary sinus • Border: well defined • Margin: corticated • Shape: round or oval 3. Internal structure • Usually: radiolucent, unilocular • Long standing: dystrophic calcification • May have septa: multilocular 4. Effect on surrounding structures Cysts are usually slowly growing… • May cause tooth resorption (sharp, curved shape), or displacement • Expansion of bone • Thinning of cortical boundaries (buccal or lingual cortical plates) • Displacement the inferior alveolar canal inferiorly or superiorly • Invagination into the maxillary sinus (maintaining a thin layer of bone) Classification Cysts of the jaws Odontogenic Developmental Non odontogenic Inflammatory Pseudo- cysts Odontogenic cysts Developmental Inflammatory 1. Radicular cyst 1. Dentigerous cyst 2. Collateral inflammatory cyst 2. Odontogenic keratocyst 3. Lateral periodontal & botryoid odontogenic cyst 4. Glandular odontogenic cyst 5. Calcifying odontogenic cyst 6. Orthokeratinized odontogenic cyst Dentigerous cyst (Follicular cyst) • A cyst that forms around the crown of an unerupted tooth. • It begins when fluid accumulates in the layers of reduced enamel epithelium or between the epithelium and the crown of the unerupted tooth. • An eruption cyst is the soft tissue counterpart of a dentigerous cyst. Dentigerous cyst Clinical Features • Second most common type of cyst in the jaws. • Develops around the crown of an unerupted tooth. • - Clinical examination: hard swelling, may result in facial asymmetry. asymptomatic a missing tooth Dentigerous cyst Radiographic Features 1. Location: • Epicenter of the cyst is just above the crown of the involved tooth, most commonly the mandibular or maxillary third molar or the maxillary canine. • Cyst is pericoronal and attached to the tooth at the CEJ. Dentigerous cyst Cyst and crown relationship Central Circumferential Lateral Dentigerous cyst • The cyst may develop from the lateral aspect of the follicle so that they occupy an area beside the crown instead of above the crown. • Cysts attached to the crown of mandibular molars may extend into the ramus. Dentigerous cyst 2. Shape and periphery • Shape: curved or circular outline. • Periphery: well- defined, corticated (If infected: loss of cortication) 3. Internal structure • Radiolucent • Associated with an impacted tooth Dentigerous cyst 4. Effect on surrounding structures • Teeth: - the impacted tooth: may be pushed apically - adjacent teeth: may be displaced or resorbed • Bone: - expansion of cortical boundaries Odontogenic keratocyst OKC • WHO classification of head and neck pathology: 1992 : odontogenic keratocyst 2005 : keratocystic odontogenic tumour (KCOT),on the basis of the tumorlike characteristics of the lining epithelium. 2017 (4th ed) : odontogenic keratocyst • Rare and locally aggressive developmental cyst • High rate for recurrence (small satellite cysts or fragments of epithelium left behind after surgical removal of the cyst) Odontogenic keratocyst Clinical Features • Age: second and third decades • Gender: slight male predominance • Asymptomatic • Painful if secondarily infected • Aspiration: a thick, yellow, cheesy material (keratin). Radiographic Features 1. Location: • Posterior mandible and ramus • epicenter is superior to the inferior alveolar nerve canal. • May appear pericoronal, resembling a dentigerous cyst Odontogenic keratocyst 2. Shape and periphery • Shape: round or oval or scalloped. • Periphery: well- defined, corticated (If infected: loss of cortication) 3. Internal structure • Unilocular radiolucency (internal keratin does not increase the radiopacity) • Multilocular radiolucency (curved internal septa may be present) Odontogenic keratocyst 4. Effect on surrounding structures • Teeth: -displacement and resorption (less than dentigerous) • Bone: - bone expansion and thinning of buccal cortex of bone - body of the mandible → minimal bucco-lingual expansion (more mesio-distal) (hence late detection) - upper ramus and coronoid process → marked bucco-lingual expansion • Inferior displacement of inferior alveolar canal • In maxilla, may occupy the entire maxillary sinus Odontogenic keratocyst Body Ramus Lateral periodontal cyst • Arises from epithelial rests in periodontium, lateral to the tooth root. • Unicystic • It is the intrabony counterpart of the gingival cyst in the adult. Clinical Features • Asymptomatic Botryoid odontogenic cysts • A variant of the lateral periodontal cyst • Appears as a cluster of small cysts Lateral periodontal cyst Radiographic Features 1. Location: • Mandible (lateral incisor to second premolar) • Occasionally in the maxilla (between the lateral incisor and the cuspid) • Usually not more than 1cm in diameter 2. Shape and periphery • Shape: round or oval • Periphery: well-defined, corticated Lateral periodontal cyst 3. Internal structure • Unilocular radiolucency • Botryoid variety: Multilocular radiolucency (grape-like appearance) 4. Effect on surrounding structures • Small cysts → loss of lamina dura • Large cysts → may displace adjacent teeth and cause expansion. Glandular odontogenic cyst (Sialo odontogenic cyst) • A rare cyst derived from odontogenic epithelium with a spectrum of characteristics including salivary gland features such as mucus-producing cells • Site: In the mandible, especially in anterior areas • Age: adults (5th and 6th decades). • Gender: High female predominance • Recurrent and aggressive lesion Glandular odontogenic cyst Radiographic Features 1. Location: • In the mandible, mostly anterior • In the maxilla, mostly in the globulomaxillary region. 2. Shape and periphery • Shape: outline is smooth or scalloped. • Periphery: well- defined, corticated Glandular odontogenic cyst 3. Internal structure • Unilocular radiolucency • Multilocular radiolucency 4. Effect on surrounding structures • Teeth: Displacement of teeth • Bone: Expansion of the outer cortical plates of the jaws and may cause perforation through the cortex Calcifying odontogenic cyst Gorlin’s cyst (COC) • According to WHO: it used to be classified as a tumor, but now it is considered a cyst. • May contain calcified tissue (dysplastic dentin) or an odontoma. Clinical Features • Slow-growing, painless swelling of the jaw (occasionally: pain) • In some cases the expanding lesion may destroy the cortical plate, and the cystic mass may become palpable as it extends into the soft tissue. • Aspiration: yields a viscous, granular, yellow fluid. Calcifying odontogenic cyst Radiographic Features 1. Location: • Equal distribution between the jaws. • Mostly anterior to the first molar, especially associated with cuspids and incisors, where the cyst sometimes manifests as a pericoronal radiolucency. Calcifying odontogenic cyst 2. Shape and periphery • Shape: outline is smooth. Or • Periphery: well- defined, corticated • Shape: irregular. • Periphery: ill- defined 3. Internal structure • Unilocular radiolucency • Mixed: Radiolucent with small foci of calcified material that appear (white flecks or small smooth pebbles) or it may show even larger, solid, amorphous masses • In rare cases: multilocular. Calcifying odontogenic cyst 4. Effect on surrounding structures • Teeth: - Displacement of teeth and resorption of roots may occur - maybe be pericoronal to a tooth, impeding its eruption • Bone: large cysts may cause perforation of cortical plates. Orthokeratinized Odontogenic cyst • WHO 1992: an uncommon orthokeratinized type of odontogenic keratocyst. • WHO 2017: it was identified as a separate entity. • It differs both clinically and histopathologically from OKC. Orthokeratinized Odontogenic cyst s are not associated with any syndromes, do not have high recurrence rates, and do not show aggressive clinical behavior. Orthokeratinized odontogenic cyst Radiographic Features 1. Location: • It usually occurs in mandible, in the molar-ramus region • May be associated with an impacted tooth 2. Shape and periphery • Shape: outline is smooth. • Periphery: well- defined Orthokeratinized odontogenic cyst 3. Internal structure • Unilocular radiolucency • Multilocular radiolucency. 4. Effect on surrounding structures • Teeth: - Displacement of neighboring teeth • Bone: - expands within bone, may displace inferior alveolar canal Radicular cyst • A radicular cyst is a cyst that most likely results when rests of epithelial cells (Malassez) in the periodontal ligament are stimulated to proliferate and undergo cystic degeneration by inflammatory products from a non-vital tooth. • Most common type of cyst in the jaws Radicular cyst Clinical Features • • Non-vital tooth (extensive caries,large restorations, or previous trauma). Asymptomatic, unless secondarily infected • May become large and cause swelling, on palpation: intact bone cortex → feels bony as bone thins → feels crepitant if outer cortex is lost → feels rubbery and fluctuant Radicular cyst Periapical Its epicenter is at the apex of the non-vital tooth Lateral Lateral to the non-vital root, mesial or distal, at the opening of an accessory root canal Residual • The cyst remaining in the jaw after removal of the offending tooth Radicular cyst Radiographic Features 1. Location: • Its epicenter is at the apex of the non-vital tooth • Latreral if related to an accessory root canal • Most radicular cysts (60%) are found in the maxilla, especially around incisors and canines. 2. Shape and periphery • Shape: curved, unless if influenced by surrounding structures such as cortical boundaries. • Periphery: well- defined and corticated. If secondarily infected: ill defined and loss of cortication Radicular cyst 3. Internal structure • Unilocular radiolucency • Dystrophic calcification may develop in long-standing cysts 4. Effect on surrounding structures • Teeth: - Displacement and resorption of the roots of adjacent teeth - may resorb the roots of the related non-vital tooth • Bone: - The outer cortical plates of the maxilla or mandible may expand in a curved or circular shape → may be thinned - Cysts may displace the mandibular alveolar nerve canal in an inferior direction. Radicular cyst Collateral inflammatory cysts 1. Paradental cyst • Inflammatory odontogenic cyst, mostly associated with pericoronitis. • Location: lateral or distal to a partially impacted lower third molar • Shape and periphery: well defined, round • Internal structure: radiolucent • Effect on surrounding structures: none, intact periodontal ligament space of related tooth 2. Buccal bifurcation cyst • Related to an impacted mandibular first or second molar • The molar may be missing or the lingual cusp tips may be abnormally protruding through the mucosa, higher than the position of the buccal cusps. • A hard swelling, buccal to the involved molar, painful secondarily infected. • Young age • Location: in the buccal furcation of the affected molar, occasionally bilateral • Shape and periphery: circular, well defined and corticated • Internal structure: radiolucent • Effect on surrounding structures: - Teeth: large cysts may displace and resorb the adjacent teeth - Bone: Expansion of buccal cortical plate Tipping of the involved molar (root tips are pushed into the lingual cortical plate) Non- Odontogenic cysts 1. Nasopalatine duct cyst 2. Nasolabial Cyst 1. Nasopalatine duct cyst (Nasopalatine canal cyst, incisive canal cyst) • Proliferation and cystic degeneration of embryonic epithelial remnants of the nasopalatine duct in the nasopalatine canal • Asymptomatic • Well-defined swelling just posterior to the palatine papilla, it’s fluctuant and blue if the cyst is near the surface. • Cystic fluid may drain into the oral cavity, patient detects a salty taste. • Nomenclature: - If extends between central incisors: median anterior maxillary cyst. - If extends posteriorly into hard palate: median palatal cyst • Location: in the nasopalatine foramen or canal, appears between the roots of the upper central incisors • Shape and periphery: circular, well defined and corticated. superimposition of the anterior nasal spine --> heart shape. • Internal structure: radiolucent • Effect on surrounding structures: • Teeth: divergence and resorption of the roots of the central incisors • Bone: - expansion of the labial and palatal cortices - floor of the nasal fossa may be displaced superiorly 2. Nasolabial Cyst • The cyst causes unilateral swelling of the nasolabial fold • May cause pain or discomfort. • When large, it may bulge into the floor of the nasal cavity • Location: soft tissue cysts, not seen on plain radiographs, needs CT or MRI • Shape and periphery: on axial CT images with use of the soft tissue algorithm with contrast, reveals a circular or oval lesion • Internal structure: radiolucent on CT images with soft tissue algorithm • Effect on surrounding structures: may cause erosion of the underlying bone, producing an increased radiolucency of the alveolar process beneath the cyst and apical to the incisors. • Nasolabial cyst on an axial CT image Pseudocysts These lesions are not true cysts 1. Simple bone cyst 2. Latent bone cyst 1. Simple bone cyst (Traumatic bone cyst, solitary bone cyst) • Asymptomatic, slow growing, non-expansile, intra-osseous, empty or fluid filled cavity having a lining of connective tissue with no epithelium. • Etiology is unknown, may be a localized aberration in normal bone remodeling or metabolism. • Related teeth are vital • Aspiration: straw-colored or serosanguineous fluid. • Location: mostly in mandibular posterior area (molar-ramus area) • Shape and periphery: - shape: oval or scalloped between roots - periphery: well defined • Internal structure: unilocular radiolucency - May appear multilocular.. But they are not true septa, the ridges produced by the scalloping of the endosteal surface of cortical bone, give the appearance of septa on a lateral view of the mandible. • Effect on surrounding structures: The lesion grows along the long axis of the bone, causing minimal expansion 2. Latent bone cyst (Stafne bone cyst, static bone cavity, lingual salivary gland depression) • A developmental anomaly • Associated with the growth of the submandibular salivary gland adjacent to the lingual surface of the mandible. • Appear as concavities in the lingual surface of the mandible where the depression is lined with an intact outer cortex. • The most common location is within the submandibular gland fossa and often close to the inferior border of the mandible. • Sialography • Location: mandibular posterior area, below the mandibular canal and anterior to the angle of mandible, in the region of the submandibular gland fossa • Shape and periphery: well defined, corticated • Internal structure: radiolucent • Effect on surrounding structures: may expand towards the inferior boarder of the mandible Classification Cysts of the jaws Odontogenic Developmental Non odontogenic Inflammatory Pseudo- cysts Reading material: • Oral Radiology: Principles and Interpretation (7th Ed.) by White, S. C. and Pharoah, M. J, published by Mosby Elseiver. Aim: The aim of this lecture is to provide an overview of the radiographic features and interpretation of cysts and cyst-like lesions of the jaws. Objectives: By the end of this tutorial, the student should be able to: • Recognize the different cysts and cyst-like lesions of the jaws on radiographs • Identify the differences between them, radiographically • Interpret those lesions by accurately and systematically describing the radiographic findings