Lecture 20 OMPR Odon and nonodon cysts 2023 PDF

Sources of epithelium within the jaw bone Odontogenic Cysts ◼ Inflammatory ◼ Odontogenic Cysts ◼ ◼ ◼ Periapical (radicular) Residual periapical Buccal bifurcation Paradental ◼ Developmental ◼ ◼ ◼ ◼ ◼ Dr Denise Trochesset ◼ Histologically, these are essentially the same – squamous epithel...

Sources of epithelium within the jaw bone Odontogenic Cysts ◼ Inflammatory ◼ Odontogenic Cysts ◼ ◼ ◼ Periapical (radicular) Residual periapical Buccal bifurcation Paradental ◼ Developmental ◼ ◼ ◼ ◼ ◼ Dr Denise Trochesset ◼ Histologically, these are essentially the same – squamous epithelial lined cysts ◼ ◼ ◼ ◼ Dentigerous Eruption Gingival cyst of newborn Gingival cyst of adult Lateral periodontal Glandular odontogenic Odontogenic keratocyst Orthokeratinized odontogenic Calcifying Odontogenic ◼ ◼ ◼ ◼ ◼ Epithelial rests of Malessez Reduced enamel epithelium Fissural cysts Odontogenic cysts Epithelial component of odontogenic tumors Salivary gland inclusions Epithelium - the cellular covering of internal and external body surfaces, including the lining of vessels and small cavities (Dorland’s medical dictionary) Periapical Cyst Remember, this entire group of cysts are central (within bone) lesions (the few exceptions are noted) Periapical Cyst Radiographic ◼ ◼ ◼ ◼ ◼ Usually appears as a well-circumscribed periapical radiolucency with widening of the PDL space and/or loss of lamina dura Typically small (< 1 cm) but can grow to large dimensions if left untreated….(Why in some and not in others?) Radiographic findings can NOT be used for definitive diagnosis (similar appearance with periapical granuloma, odontogenic tumors, early COD {Cemento Osseous Dysplasia}, etc) Root resorption (blunt) is not uncommon Lateral radicular cyst appears on the lateral surface of the root of a non-vital/non-responsive tooth Inflammatory Odontogenic Cysts ◼ ◼ ◼ ◼ ◼ ◼ ◼ aka radicular cyst, inflammatory cyst The most common cyst of the jaws Any age (peak in 3rd - 6th decades, rare in 1st decade) No sex predilection MX > MD (anterior MX most common) Usually painless and found on routine exam Involved tooth usually non-vital/non-responsive with thermal and electric pulp testing Periapical Cyst Histology ◼ ◼ ◼ Vascular fibrous connective tissue (FCT) containing a pathological space lined by non-keratinized (usually stratified) squamous epithelium Chronic inflammatory cells seen in the FCT (lymphocytes, plasma cells, macrophages, etc.) May also see nonspecific signs of inflammation (Russel bodies, cholesterol clefts, multi-nucleated giant cells, and dystrophic calcifications in the FCT and Rushton bodies may be seen within the epithelium) Cystic space Epithelium Fibrous connective tissue stroma Connective tissue Epithelium - demonstrating hyperplasia and anastomosis of rete pegs Cystic space Cyst wall Rushton bodies Keratin pearl Residual Cyst Cholesterol/cholesterin clefts ◼ ◼ ◼ Radiographically, see a well defined round to oval radiolucency in the site of a previous extraction After a tooth is extracted, the residual cells of the cyst lining and inflammatory cells continue to proliferate Histologically identical to the radicular cyst Residual Cyst Paradental Cyst ◼ ◼ ◼ ◼ Some controversy over this designation, some think this is an inflammatory cyst and some think they are developmental cysts Etiology remains unclear Radiolucent area noted, most frequently, along the distal aspect of an impacted or partially erupted third molar Have been associated with enamel extensions into furcation areas of the involved teeth Buccal Bifurcation Cyst ◼ ◼ ◼ ◼ ◼ Thought to be similar to a paradental cyst except that the location is central on the buccal aspect of mandibular first molars Etiology remains unclear Most commonly seen with eruption of the permanent first molar Clinical swelling and usually tenderness of soft tissue over involved area Radiolucency best seen with an occlusal radiograph or CBCT Buccal Bifurcation Cyst Treatment ◼ Enucleation of cyst ◼ Some cases reported to resolve on their own without surgery Some cases resolve with daily irrigation of buccal pocket with saline/hydrogen peroxide ◼ ◼ tooth extraction unnecessary Developmental Odontogenic Cysts Dentigerous Cyst ◼ ◼ ◼ ◼ aka follicular cyst Most common type of developmental odontogenic cyst (~20% of all epithelial lined cysts of the jaw) Originates by the separation of the follicle from the crown of an unerupted tooth Pathogenesis appears to be accumulation of fluid between the tooth and the reduced enamel epithelium Dentigerous cyst Radiographic ◼ ◼ ◼ Well-defined radiolucency, often sclerotic border (infected cysts may be ill-defined/poorly circumscribed) Large lesions may give the appearance of a multilocular lesion due to residual bone trabeculae, but dentigerous cysts are grossly and histologically unilocular and a true multilocular lesion probably does not exist Distinction between a small dentigerous cyst and an enlarged or hyperplastic follicle is difficult ◼ ◼ rule of thumb – greater than 4-5 mm of radiolucency to call an area a dentigerous cyst Radiographic features are NOT diagnostic (other lesions can have the same or similar radiographic appearance) Dentigerous Cyst ◼ ◼ ◼ ◼ ◼ ◼ Attached to the tooth at the CEJ Most often involve mandibular third molars (rarely involves unerupted deciduous teeth) Most commonly present in 2nd and 3rd decades Small cysts typically asymptomatic and picked up on routine radiographic exam Large lesions may show expansion of bone Cysts may become infected, especially when associated with partially erupted tooth Dentigerous Cyst Dentigerous Cyst Histology ◼ ◼ Fibrous connective tissue (FCT) containing a pathologic space lined by epithelium (cuboidal to SSE) Flat interface between FCT and epithelium (unless inflamed) ◼ ◼ Inflamed cysts demonstrate downward proliferation (hyperplasia) and anastomosis of rete pegs Stratified squamous epithelium, often 2-4 layers thick, typically nonkeratinizing Epithelium Dentigerous Cyst Cystic space Connective tissue Dentin of tooth Epithelial lining Goblet cells (mucous cells) Carcinoma Arising in Odontogenic Cyst Cilia ◼ ◼ ◼ ◼ ◼ Epithelial metaplasia Respiratory epithelium (can see this with MX cysts) ◼ ◼ ◼ A rare occurrence aka odontogenic carcinoma Thought to be 1-2% of all oral cavity carcinomas Mean age at diagnosis is 60 2:1 male:female ratio Most commonly (~60%) in area of a residual periapical cyst Irregular and ragged radiographic outline Why it is recommended to remove cysts in the jaws How would you treat this? Eruption Cyst ◼ ◼ ◼ ◼ ◼ aka eruption hematoma Soft tissue counterpart of a dentigerous cyst Results from accumulation of fluid in the follicular space when the tooth has erupted over the alveolar bone *NOT in bone* Usually seen in first decade Most often involves 1st permanent molar and maxillary incisors Eruption Cyst ◼ ◼ ◼ Although frequently normal mucosal color, surface trauma (ex. chewing) may result in bleeding into the cystic space – cyst will then appear more purple or blue in color Usually soft or fluctuant upon palpation Unless symptomatic, no treatment required, cysts resolve upon eruption of teeth Cyst lining Cysts of the Newborn Palatal ◼ Palatal cysts ◼ Bohn’s nodules ◼ Epstein’s pearls ◼ Vascular FCT ◼ ◼ ◼ ◼ ◼ ◼ Oral mucosa Cysts of the Newborn Gingival ◼ ◼ ◼ ◼ ◼ ◼ ◼ ◼ Dental lamina cysts (Gingival cyst of the newborn) 1-3 mm creamy white papules (keratin filled cysts) Found superficially on the alveolar ridge mucosa MX > MD *NOT in bone* Spontaneously resolve (degenerate or rupture) No treatment is necessary Rarely seen after 3 mos. of age Scattered over HP, often junction of HP and SP Along median palatal raphe Seen in 60-80% of neonates 1-3 mm cream to white papules (keratin filled cysts) *NOT in bone* Resolve (degenerate or rupture) on their own No treatment is required, usually gone 3-6 mos of age Gingival Cyst of the Adult ◼ ◼ Soft tissue counterpart of the lateral periodontal cyst *NOT in bone* Derived from dental lamina rests ◼ ◼ ◼ ◼ rests of Serres Uncommon lesion 60-75% mandibular canine/premolar area, most common location on the facial/buccal aspect 5th and 6th decade most common Gingival Cyst of the Adult ◼ ◼ ◼ Painless dome-like swellings up to 5 mm in diameter Often with a bluish or grayish hue Histology similar to lateral periodontal cyst ◼ ◼ ◼ ◼ Thin flattened squamous epithelium Focal plaque-like thickenings (often with glycogen rich clear cells) Simple surgical excision Unlikely to recur Cyst lining Cyst lumen Surface mucosa Lateral Periodontal Cyst Lateral Periodontal Cyst ◼ ◼ and Botryoid odontogenic cyst ◼ ◼ ◼ A developmental cyst believed to arise from dental lamina rests Represents the intrabony counterpart of the gingival cyst of the adult Term reserved for cysts that occur in the lateral periodontal region, in which an inflammatory origin or the diagnosis of odontogenic keratocyst have been excluded Commonly asymptomatic and found on routine radiographic exam Associated teeth test vital/responsive with electric and thermal pulp testing Lateral Periodontal Cyst ◼ ◼ ◼ Most commonly found after age 30 Males>Females ~65% mandibular canine/premolar area ◼ ◼ ◼ ◼ Can also be seen between canine and lateral incisor Present as well circumscribed unilocular radiolucencies located lateral to tooth root Most often 0.5-1.0 cm in diameter Radiographic features are NOT diagnostic, other lesions can present with the same radiographic findings (ex. radicular cysts from an accessory canal, OKC) Lateral Periodontal Cyst ◼ ◼ ◼ ◼ Histologically, appear as a pathologic space in connective tissue with thin squamous epithelium lining the lumen Epithelial cells may be typical squamous cells or more plump cuboidal cells Have foci of plaque-like thickenings (cells increase to 8-10 cells thick) and glycogen-rich clear cells Treatment consists of conservative enucleation Botryoid Odontogenic Cyst ◼ Considered a variant of lateral periodontal cyst ◼ ◼ ◼ ◼ ◼ Similar age range Same location Botryoid odontogenic cysts, grossly and microscopically, show a grape-like cluster of small individual cysts May appear either unilocular or multilocular on radiographs, depending on size of the lesion Cyst lining similar to lateral periodontal cyst Glandular Odontogenic Cyst ◼ ◼ ◼ A rare odontogenic cyst which exhibits features of glandular differentiation within the epithelium Presumably represents the pluripotentiality of odontogenic epithelium Can be locally aggressive ◼ ◼ Glandular Odontogenic Cyst ◼ Mean age 49 ◼ ◼ ~ 75% of reported cases in mandible Anterior lesions ~ 25% recurrence rate after conservative treatment Usually asymptomatic unless inflamed ◼ ◼ ◼ Rare before age of 20 ◼ ◼ More common May cross the midline Uni- or (more often) multilocular radiolucency Well-defined with corticated border Glandular Odontogenic Cyst ◼ ◼ ◼ ◼ The cyst lining is squamous epithelium with varying thickness with focal areas of columnar cells with intracellular mucin (goblet cells) The surface epithelium may show cilia In areas of thickened lining, can see a swirling nest-like pattern to the epithelial cells The epithelium demonstrates cyst-like spaces lined by cuboidal cells ◼ ◼ gives the appearance of “gland” formation Histologic differential diagnosis includes low grade mucoepidermoid carcinoma (salivary gland tumor) ◼ No MAML2 gene rearrangement, which MECa would have Gland-like spaces within the epithelium Gland-like spaces within the epithelium “Primordial” Cyst ◼ ◼ ◼ ◼ ◼ The concept of primordial cyst has been controversial and confusing in the literature Originally meant to describe a cyst which develops in bone at a site where a tooth was meant to develop (usually a third molar) In the 1950’s, the histology of this cyst became confused with that of an odontogenic keratocyst (it is now thought that most of the reported cysts were actually OKCs) If this lesion exists, it is truly rare and would have histology distinct from OKC In the current literature, reference to this lesion is almost nonexistent Odontogenic Keratocyst Odontogenic Keratocyst Keratocystic odontogenic tumor ◼ aka OKC ◼ 2005 WHO - keratocystic odontogenic tumor (KOT), now back to OKC ◼ Has a distinct histologic pattern and more aggressive biologic behavior than conventional odontogenic cysts Growth and expansion of this lesion due not only to osmotic effects/pressure, but to unusual gene expressions including: ◼ ◼ ◼ ◼ ◼ Expresses Ki-67 (high rate of cell proliferation) Overexpression of Bcl-2 (antipoptotic protein) Overexpression of MMP’s 2 and 9 (thought to allow growth into connective tissue) Mutation of PTCH, a tumor suppressor gene ◼ when PTCH is nonfunctional → cell proliferation ◼ ~ 60% present in second and third decade, but can occur at any age Mandible affected in 60-80% of cases ◼ 25-40% of cases involve an unerupted tooth ◼ Make up ~10-15% of all odontogenic cysts 5% of patients have multiple cysts and another 5% are associated with nevoid basal cell carcinoma syndrome (Gorlin syndrome) ◼ ◼ ◼ ◼ tendency to occur in posterior mandible and ramus Radiographically appear similar to dentigerous cyst Site Distribution of OKC Odontogenic Keratocyst Recurrence Rate ◼ ◼ ◼ Benign, but locally aggressive biologic behavior Solitary OKCs have ~10% recurrence rate with appropriate treatment Multiple OKCs have ~ 30% recurrence rate Radiographic ◼ ◼ ◼ ◼ ◼ ◼ ◼ Syndrome OKC >Multiple OKC>Solitary OKC> Conventional odontogenic cysts Usually a well-circumscribed radiolucency with smooth, often corticated margins Cysts may be ◼ ◼ Unilocular (most common) Multilocular (larger lesions) Small cysts are typically asymptomatic and picked up on routine radiographic exam Larger cysts may or may not be asymptomatic Cysts tend to grow in an antero-posterior direction prior to lateral growth (therefore cysts are usually quite large when they start to expand the cortical plate) Radiographic findings are NOT diagnostic for the lesion (dentigerous cyst, ameloblastoma, etc. may appear similar) Odontogenic Keratocyst ◼ ◼ ◼ ◼ Diagnosis of OKC is based on the characteristic histologic (not radiographic) findings Fibrous connective tissue (FCT) containing a pathologic space lined by stratified squamous epithelium which is 6 to 8 cells in thickness Interface between the epithelium and FCT is typically flat, although some cases will show basilar budding (thought to be a reason for increased risk of recurrence) Epithelium lining is thin, friable and easily detached from the FCT, often see lining separated from FCT on histologic section (thought to be a reason OKCs have a higher risk of recurrence versus other odontogenic cysts, lining may not be completely removed at the time of surgery) Odontogenic Keratocyst ◼ ◼ ◼ ◼ ◼ Basal cells of the epithelium are uniform, palisaded and hyperchromatic Surface of epithelial lining shows flattened parakeratin often exhibiting a wavy or corrugated profile Keratin is noted in the cyst lumen (grossly appears as a cream colored “cheesy” paste-like substance) 10-25% of cases show satellite or “daughter” cysts in the connective tissue wall (thought to be another reason the recurrence rate is so high for OKCs) FCT wall typically is free of inflammatory cell infiltrate ◼ Epithelium lining Connective tissue wall Keratin scales in cyst lumen If inflamed, the typical histologic features of OKC may be lost Odontogenic Keratocyst Connective tissue Epithelium Treatment Options OKC Enucleation Curettage ❑ Marsupialization (decompression) ❑ Peripheral ostectomy ❑ ❑ Daughter cyst in the connective tissue wall ❑ Carnoy’s Nevoid Basal Cell Carcinoma Syndrome ◼ ◼ ◼ ◼ ◼ ◼ ◼ solution Resection ❑ Medications targeted to PTCH ❑ Long term follow-up aka Gorlin syndrome, Basal Cell Nevus - Bifid Rib Syndrome Autosomal dominant inheritance Syndrome findings include (there are many others): ◼ ❑ ◼ ◼ ◼ Multiple basal cell carcinomas of the skin Odontogenic keratocysts (frequently multiple) Intracranial calcification of the falx cerebri Rib anomalies (bifid, splayed, partially missing) Epidermal cysts of the skin Palmar/plantar pitting Medulloblastoma Mutation of PTCH (tumor suppressor gene) Nevoid Basal Cell Carcinoma Syndrome ◼ BCCs present as indurated papules with small vessels on the surface ◼ ◼ Ulcerated and umbilicated (old term “rodent” tumors – people thought they looked like a mouse or rat took a bite out of the skin) With the syndrome, there are so many BCCs that some may affect vital structures (or rarely metastasize) Nevoid Basal Cell Carcinoma Syndrome ◼ ◼ Prognosis depends on progression of skin tumors BCC treatments ◼ ◼ surgery (MOHS), curettage, RT, cryotherapy, photodynamic therapy with photosensitizer and topical medications (e.g imiquimod and 5-FU) New medication ◼ ◼ Vismodegib – inhibits sonic hedgehog pathway by binding smoothened (SMO) May be suppressive rather than curative ◼ ◼ ◼ Multiple basal cell carcinomas After ~7-8 months a significant proportion get resistance (use of alternate pathways) May cause hair and taste loss Some data showing it also helps suppress growth of OKCs CALCIFYING ODONTOGENIC CYST Calcifying Odontogenic Cyst (COC) ◼ Cystic COC ◼ (Calcifying Cystic Odontogenic Tumor, Gorlin Cyst, Ghost Cell Tumor) ◼ ◼ Solid COC (dentinogenic ghost cell tumor) ◼ ◼ ◼ ◼ COC Radiographic ◼ ◼ Usually a well-circumscribed unilocular radiolucency One third to one half show radiopaque structures within the radiolucency ◼ ◼ ◼ ◼ ◼ A mixed radiolucent/radiopaque lesion ~ 65% occur in incisor canine area Female > Male May cause resorption or displacement of roots One third are associated with unerupted teeth ◼ usually a canine Usually unilocular, as matures mixed RL/RO COC with odontoma (~ 20%) Often demonstrate a more aggressive behavior Only about 5% are solid WHO once considered them calcifying cystic odontogenic tumor (CCOT) now back to COC and dentinogenic ghost cell tumor Odontogenic ghost cell carcinoma COC ◼ Mean age 30 ◼ ~85% presents anterior to molars MX=MD ~52% MX and 48% MD ~ 15% extraosseous (peripheral), found in older age group (~ 50 years of age) ◼ ◼ ◼ ◼ most between ages of 20-40 May occur in association with odontomas, ameloblastomas, and adenomatoid odontogenic tumors ◼ COC Histology FCT containing a pathologic space lined by ameloblastic-like epithelium (palisading cuboidal to columnar basal cell layer with prominent hyperchromatic nuclei and more superficial cells resembling stellate reticulum) of varying thickness in ◼ ◼ COC Histology some cases there is no cyst lumen – solid tumor See numerous eosinophilic “ghost cells” thought to be the result of abnormal keratinization ◼ ◼ ◼ Masses of ghosts cells may fuse to form sheets of eosinophilic, amorphous, acellular material within the epithelium Calcification within the ghost cells is common ◼ ◼ This is why radiopacity is seen in radiographs If calcifications have not yet formed, lesion will appear radiolucent, not mixed radiolucent/radiopaque Ghost cells are altered epithelial cells that have lost their nuclei, but have kept the basic outline of the cell COC ◼ ◼ ◼ ◼ ◼ Treatment typically consists of enucleation with peripheral ostectomy – good prognosis Follow up is long term because some of the solid tumors have a more aggressive behavior Peripheral lesions are treated with excision When associated with another tumor, ameloblastoma for example, the treatment is based on the more aggressive tumor Odontogenic ghost cell carcinoma is rare, shows cytologic atypia histologically and has an unpredictable biologic behavior (5 year survival ~ 70%) “Fissural” Cysts Non-Odontogenic Cysts Nasolabial cyst Globulomaxillary cyst (historic) ❑ Nasopalatine (incisive canal) cyst ❑ Incisive papilla cyst ❑ Median palatal cyst ❑ Median mandibular cyst (historic) ❑ ❑ Nasolabial Cyst ◼ ◼ ◼ ◼ ◼ aka Nasoalveolar cyst Thought to be caused by either epithelial remnants of the nasolacrimal duct or cells left after fusion of the maxillary, medial and lateral nasal processes during development of the midface Rare soft tissue cyst of the upper lip, lateral to the midline *NOT in bone* Clinically see a swelling which can cause elevation of the ala of the nose Intraorally see a swelling in the maxillary vestibule lateral to the midline “Globullomaxillary Cyst” ◼ ◼ ◼ In quotations because this was initially thought to be a cyst derived from epithelial remnants left after fusion of the globular portion of the nasal process with the maxillary process, it is now known that these two processes are united from the start and that no “fusion” occurs A term used to describe a cyst in a particular anatomic location it is not a diagnosis When biopsied these cysts are odontogenic in origin (lateral granulomas or cysts, OKCs, COCs, etc.) ◼ ◼ ◼ An odontogenic cyst that forms in the area between the maxillary lateral incisor and the canine roots Frequently causes displacement of the roots Presents as a “inverted pear” shaped well-circumscribed radiolucency Nasolabial Cyst ◼ ◼ ◼ ◼ ◼ ◼ Pain is uncommon, unless cyst becomes infected Peak in 4th and 5th decades 3 to 4 times more common in females ~ 10% of cases are bilateral Histologically see a pathologic space lined with pseudostratified columnar epithelium, often with cilia and goblet cells (What type of epith?) Treated by surgical excision via intraoral approach, usually do not recur Nasopalatine Duct Cyst ◼ ◼ ◼ ◼ ◼ ◼ aka incisive canal cyst, nasopalatine canal cyst Most common non-odontogenic cyst of the oral cavity Thought to arise from epithelial remnants of the nasopalatine duct which, embryologically, connects the oral and the nasal cavities Peak presentation in the 4th to 6th decades, but can occur at any age Commonly present with swelling of the anterior palate Most are asymptomatic, but they may have pain or drainage Nasopalatine Duct Cyst ◼ ◼ ◼ ◼ Radiographic exam reveals a well-circumscribed radiolucency on the midline of the anterior hard palate between and apical to the central incisors The radiolucency often have an oval or inverted pear shape with a sclerotic border Superimposition with the nasal septum can create an appearance of the classic “heart” shape Incisive papilla cyst (aka cyst of the palatine papilla) is a soft tissue cyst (no bone involvement) located in the same area Nasopalatine Duct Cyst ◼ ◼ ◼ ◼ Histologically, the lining of the cyst can vary from SSE to pseudostratified columnar to simple columnar to cuboidal Cilia and goblet cells may be present (indications of respiratory epithelium) The fibrous connective tissue wall contains moderate sized nerve bundles and small muscular walled arteries and veins (represents the nasopalatine neurovascular bundle ) Treated by surgical excision, recurrence is rare Median Palatine Cyst ◼ Thought to represent a more posteriorly placed nasopalatine duct cyst Surgical Ciliated Cyst of the Maxilla “Median Mandibular Cyst” ◼ ◼ ◼ ◼ A controversial cysts whose existence is questioned Originally thought to arise from the fusion of the “halves” of the mandible, but current embryology finds that the mandible forms from a single bilobed process, therefore, no epithelial remnants would be found Like the globulomaxillary cyst, it is thought that cysts in this area represent odontogenic cysts or tumors A term used to describe a cyst in a particular anatomic location not a definitive diagnosis ◼ ◼ ◼ ◼ ◼ ◼ Occurs after trauma or sinus surgery (iatrogenic reactive not neoplastic) A portion of the sinus lining is separated from the sinus and forms an epithelial lined cavity in bone Cavity fills with mucin produced by the mucous cells of the cyst lining These cysts enlarge as the intraluminal pressure increases, causing destruction of bone Occur frequently after a Caldwell-Luc procedure and sometimes with difficult maxillary extractions These cysts are reported with higher frequency in Japan Respiratory epithelium (sinus epithelium) Aneurysmal Bone Cyst ◼ Pseudocysts ◼ ◼ ◼ ◼ Aneurysmal Bone Cyst ◼ ◼ ◼ ◼ ◼ Gross appearance of a “blood soaked sponge” Variously sized blood filled sinusoidal spaces (not lined by endothelium) surrounded by cellular fibroblastic tissue Woven (reactive, immature) bone may be seen in the FCT The connective tissue can contain multinucleated giant cells and extravasated red blood cells Wall of the aneurysmal bone cyst can have a histology similar to the following: ◼ ◼ ◼ Central giant cell granuloma Cherubism Brown tumor of hyperparathyroidism A pseudocyst – not epithelial lined Most common site in the body is long bones or vertebrae In the jaws, most frequently seen in the 1st and 2nd decade MD > MX Presents with a clinical swelling, frequently a rather rapid swelling, often with pain and/or paresthesia (signs which can be suggestive of the presence of a malignant or aggressive lesion) Aneurysmal Bone Cyst ◼ ◼ ◼ ◼ ◼ Etiology is unclear, may result from trauma or a vascular malformation, but most agree that it is a reactive and not a neoplastic lesion 2/3 of lesions occur de novo (thought to be neoplastic) or in the site of a pre-existing lesion (ex. fibrous dysplasia or central giant cell granuloma, thought to be reactive) Radiographic exam shows a radiolucency which can be either unilocular or multilocular in appearance Borders are variable, often irregular in shape and may be illdefined (again, giving the suggestion of malignancy) Teeth may be displaced and may see cortical expansion and thinning Aneurysmal Bone Cyst ◼ ◼ ◼ Multinucleated giant cells Antral Pseudocyst ◼ Antral pseudocysts differ in the following ways from the surgical ciliated cyst: Antral psuedocysts are not epithelial lined spaces They are not within the bone but are in the sinus ◼ They develop as an accumulation of an inflammatory exudate (often serum) between the sinus epithelial lining and the bone ◼ Appears as a dome shaped elevation of the floor of the sinus ◼ ◼ Simple Bone Cyst ◼ ◼ ◼ ◼ ◼ ◼ ◼ aka traumatic bone cyst A benign, empty or fluid filled, cavity in bone which is devoid of an epithelial lining – a pseudocyst Etiology is uncertain, theories include: trauma, ischemic necrosis of medullary space, or cystic degeneration of a primary bone lesion Thought to be reactive, not neoplastic In jaws, most likely in the 2nd decade Almost exclusively the mandible Twice as common in males Simple Bone Cyst ◼ ◼ ◼ ◼ ◼ ◼ ◼ Radiographic exam reveals a well-circumscribed radiolucency with an irregular outline Tendency to “scallop” around and between roots (highly suggestive, but not diagnostic of this lesion) Teeth involved are vital/responsive Been reported in association with florid cemento-osseous dysplasia Histologically, see only scant delicate vascularized FCT Treatment is exploration and curettage of space to create bleeding. Clot will organize and allow bone repair Recurrence is rare Vascularity is predominantly “low flow”, therefore not as much concern for bleeding upon surgical removal (vs central hemangioma) Treatment is surgical enucleation and curettage often after SAE (selective arterial embolization) Lesions can recur (most data from long bones) Osteoporotic Bone Marrow Defect ◼ ◼ ◼ ◼ ◼ ◼ ◼ aka hematopoietic bone marrow defect Uncommon finding Typically asymptomatic and found on routine radiographic exam An area of hematopoietic marrow of sufficient size to produce an area of radiolucency Etiology unclear, may be hyperplasia of marrow due to need for RBCs or abnormal regeneration of bone after an extraction or persistence of fetal marrow > 75% of cases are in females ~ 70% occur in the posterior MD, often in an edentulous area Osteoporotic Bone Marrow Defect ◼ ◼ ◼ ◼ Irregularly shaped radiolucency with either a well defined or ill-defined border (so can be in D/D with malignancies) Histologically, a cellular hematopoietic marrow is seen with fewer than the normal numbers of fat cells Must biopsy to make a definitive diagnosis No further treatment is then necessary Stafne Bone Cyst ◼ ◼ ◼ ◼ ◼ ◼ ◼ ◼ aka static bone cyst, Stafne defect An asymptomatic focal concavity of the cortical bone on the lingual aspect of the MD A pseudocyst, not a true cyst Most commonly found near the angle of the mandible below the inferior alveolar nerve (but also seen in the anterior MD) When biopsied, usually get normal salivary gland tissue, but most likely because gland has expanded into the defect Believed to be developmental in origin, but usually noted only in adults > 80% in Males Radiographic appearance of lesions in the posterior MD are usually pathognomonic and no further treatment is necessary Less common location Dermoid Cyst ◼ Soft Tissue Cysts of the Neck ◼ ◼ ◼ ◼ ◼ Dermoid Cyst ◼ ◼ ◼ ◼ Upon palpation, cyst feels doughy or rubbery Histologically, the cystic space is filled with keratinaceous debris and sebum The cyst lining appears similar to skin: SSE with orthokeratinized surface, prominent granular cell layer, and skin appendages (adnexal structures) in the FCT wall (ex. sebaceous glands, hair follicles and sweat glands) Treatment is surgical excision, recurrence is rare Benign developmental cystic lesion considered a form of teratoma Can be found anywhere, but in the oral cavity they are ususally located in the anterior floor of the mouth (FOM) Usually found on the midline Depending on whether the cyst is above or below the mylohyoid muscle, the lesion will cause swelling into the oral cavity elevating the tongue or under the chin in the submandibular area, respectively Painless and slow growing, if not infected Most common in the 1st and 2nd decade Epidermoid Cyst ◼ Epithelium ◼ ◼ ◼ Hair follicle ◼ ◼ ◼ ◼ Sebaceous gland ◼ aka infundibular cyst, epidermal inclusion cyst, “sebaceous” cyst (laymen’s term, not really sebaceous) A very common skin cyst Often occur after inflammation of a hair follicle Young adults more likely to have cysts of the face, older adults to have cysts of the back Males > Females Associated with Gardner’s syndrome Subcutaneous nodular, firm to fluctuant, papule Cavity lined by SSE with a granular layer and abundant keratin on epithelial surface and in lumen, no adnexal structures in cyst wall Treatment is excision, recurrence is rare Thyroglossal Duct Cyst ◼ ◼ ◼ ◼ ◼ ◼ The most common developmental cyst of the neck Develops from epithelial remnants of the tract which forms when the thyroid anlage descends into the neck from an area that later forms the foramen caecum Follows a path that goes anterior to the hyoid bone and ends below the thyroid cartilage Cyst classically forms at the midline 60-80% of cysts are below the hyoid bone Most commonly present in the first 2 decades ◼ Thyroglossal Duct Cyst ◼ ◼ ◼ ◼ ◼ ◼ ◼ Cysts are typically painless fluctuant swellings, unless infected If the cyst remains attached to the hyoid bone or the tongue, it will move up and down when swallowing or protruding the tongue ~ 1/3 will present with a fistulous tract Cyst lining can be vary from SSE to pseudostratified columnar with cilia FCT wall often contains thyroid tissue Treatment is surgical excision, recurrence are not uncommon Rare cases of thyroid carcinoma developing in these cysts have been reported ~ 50% prior to 20 years of age Branchial Cleft Cyst ◼ ◼ ◼ ◼ ◼ aka cervical lymphoepithelial cysts Located on the lateral aspect of the neck, usually anterior to the sternocleidomastoid muscle Most commonly presents in the 3rd to 5th decades Clinically presents as a soft fluctuant swelling ranging from 1 to 10 cm in diameter Etiology is disputed, some think it is from remnants of the branchial cleft, others think it is cystic change of parotid gland epithelium which became entrapped in a cervical lymph node during development Branchial Cleft Cyst ◼ ◼ ◼ ◼ ◼ 2/3 of the reported lesions have been on the left side Histologically, ~90% of cysts are lined by SSE which may or may not be keratinized Wall of the cyst contains lymphoid tissue often with germinal center formation Treated by surgical excision, recurrence is rare Although cyst in general are uncommon in the parotid gland, can see multiple lymphoepithelial cysts bilaterally in HIV positive patients ◼ ◼ Oral Lymphoepithelial Cyst ◼ ◼ ◼ ◼ ◼ ◼ ◼ ◼ ◼ Uncommon lesion Thought to develop in oral lymphoid tissue Most frequent location is FOM (> 50%) Usually less than 1 cm in diameter May feel firm or soft on palpation Typically creamy to yellow in color Painless unless infected Cystic space lined by SSE (typically parakeratinized) surrounded by FCT with dense lymphoid aggregates, often with germinal center formation Treated with surgical excision, recurrence is rare These cases present as painless uni- or bilateral swellings of the parotid glands If seen in someone who does not have a history of HIV, they should be tested