Cysts

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Table of Contents

  1. Aneurysmal Bone Cysts
  2. Calcifying Odontogenic Cyst (COC)
  3. Dentigerous Cyst (formerly follicular cyst)
  4. Lateral Periodontal Cyst
  5. Nasopalatine Duct Cyst (incisive canal cyst)
  6. Odontogenic Keratocysts
  7. Radicular Cysts
  8. Thyroglossal Duct Cysts
  9. Traumatic Bone Cyst (solitary bone cyst, hemorrhagic bone cyst, extravasation cyst, simple bone cyst)

ANEURYSMAL BONE CYSTS

Aneurysmal Bone Cysts are benign but locally aggressive tumor-like vascular lesions. They are more common in pediatric dental patients and can interfere with the growth plates of bones. Aneurysmal bone cysts are most frequently seen in the femur, tibia, and vertebrae, but can develop in cranial bones. The etiology is unknown but vascular malformations may be linked to bone trauma. The common clinical presentation includes:

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Subperiosteal shell of reactive bone.
  • Blood and hemosiderin-filled cystic cavities that contain septa of trabeculated bone.
  • Stroma that contains fibroblasts, spindle cells, and multinucleated giant cells.

Your differential diagnosis should include:

Treatment options include:

  • Intralesional curettage.
  • Surgical excision.
  • En bloc (complete) excision. 

CALCIFYING ODONTOGENIC CYST

Calcifying Odontogenic Cyst (COC) is a rare developmental odontogenic cyst with characteristic histopathological features and a propensity to calcify. COC originates from the residual odontogenic epithelium and is often seen in conjunction with other tumors. COC, dentinogenic ghost cell tumors (DGCT) and ghost cell odontogenic carcinomas (GCOC) combined form a group termed odontogenic ghost cell lesions (OGCL) of the jaws. The common clinical presentation includes:

  • Well-defined unilocular radiolucency with scattered opacities.
  • May be associated with the crown of an unerupted tooth.
  • Tooth displacement may be evident.
  • Possible extraosseous variant (usually anterior to first molar).
  • May be more solid than cystic (odontogenic ghost cell tumor).

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Stratified squamous lining with prominent basal layer.
  • Characteristic ghost cell keratinization that may undergo dystrophic calcification.
  • Possible foreign body reaction when ghost cells come in contact with connective tissue.
  • Histologically similar to ameloblastoma.

Your differential diagnosis should include

  • Calcifying epithelial odontogenic tumor.
  • Ossifying fibroma.
  • Ameloblastic fibro-odontoma.

Treatment options include:

  • Enucleation.
  • Surgical excision.

DENTIGEROUS CYST

Dentigerous Cyst (formerly follicular cyst) is an odontogenic cyst that develops from the dental follicle of an unerupted or impacted tooth. The developmental variant is the most common type, seen when fluid accumulates between the tooth crown and the reduced enamel epithelium lining the follicle. The rare inflammatory dentigerous cyst is usually associated with the roots of a nonvital primary tooth, where the spread of periapical inflammation may affect the germ of the neighboring permanent tooth. There is a small risk of neoplastic transformation (ameloblastoma or squamous cell carcinoma). The common clinical presentation includes:

  • Well-defined unilocular radiolucency enclosing the crown of unerupted tooth.
  • Usually associated with mandibular third molars and maxillary canines.
  • Mostly asymptomatic (incidental discovery).
  • Adjacent root resorption may be evident.
  • Painless bony expansion may occur.
  • Cortex may be thinned but rarely perforated.

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Fine needle aspiration produces a straw colored fluid.
  • Cystic lesion lined by nonkeratinized epithelium.
  • Loosely arranged collagen bundles that may contain scattered odontogenic epithelial rests.

Your differential diagnosis should include:

  • Odontogenic keratocyst.
  • Unicystic ameloblastoma.
  • Central giant cell granuloma.
  • Large radicular cyst.
  • Ameloblastoma.

Treatment options include

  • Tooth extraction and enucleation.
  • Marsupialization prior to excision if large.

LATERAL PERIODONTAL CYST

Lateral Periodontal Cyst is a relatively rare non-inflammatory odontogenic cyst that originates from epithelial rests within the periodontal ligament (dental lamina, reduced enamel epithelium, or rests of Malassez). It is a harmless and painless oral lesion that is usually found incidentally on routine radiographs. The common clinical presentation includes:

  • Well defined round to ovoid unilocular (perhaps multilocular) radiolucency
  • Thin opaque (corticated) margin.
  • Located lateral to vital tooth roots.
  • May cause root resorption, tooth displacement, expansion, and pain.
  • In the mandible it is most often found in the canine and premolar region.
  • In the maxilla it is most often found in the lateral incisor area.

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Thin, non-keratinized epithelial lining with cuboidal cells.
  • Nodular epithelial thickening along cyst lining.

Your differential diagnosis should include:

  • Lateral radicular cyst (inflammatory).
  • Odontogenic keratocyst.
  • Odontogenic tumor.
  • Gingival cyst.
  • Glandular odontogenic cyst.

Treatment options include:

  • Enucleation.
  • The botryoid variant requires more aggressive curettage.

NASOPALATINE DUCT CYST

Nasopalatine Duct Cyst (incisive canal cyst) is a relatively common non-odontogenic developmental cyst derived from the embryogenic remnants of nasopalatine duct. Most are asymptomatic and discovered during routine radiography. The common clinical presentation includes:

  • Well-defined round to ovoid (sometimes heart-shaped) radiolucency in anterior maxillary midline.
  • Usually greater than 5mm in diameter.
  • Opaque (corticated) margin.
  • Lamina dura will usually be intact and the adjacent tooth pulp vital.
  • May cause soft tissue swelling and teeth displacement.

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Squamous ciliated (respiratory) and cuboidal epithelium.
  • Squamous epithelium may show pseudostratification.

Your differential diagnosis should include:

  • Periapical pathology.
  • Radicular cyst.
  • Odontogenic keratocyst.
  • Orthokeratinized odontogenic cyst.
  • Dentigerous cyst.
  • Glandular odontogenic cyst.

Treatment usually involves surgical cyst enucleation and histopathological examination.

ODONTOGENIC KERATOCYST

Odontogenic Keratocysts are benign intraosseous odontogenic lesions derived from the dental lamina, known for their aggressive behavior and relatively high recurrence rate. A large proportion of lesions are associated with the inactivation of the PTCH tumor suppressor gene and may be termed a keratocystic odontogenic tumor. The common clinical presentation includes:

  • Well-defined unilocular or multilocular radiolucency associated with a tooth/teeth.
  • Often (40%) seen in a dentigerous relationship, but may be apical or lateral to an impacted tooth.
  • Can be found in any area of maxilla or mandible.
  • Rarely may arise in gingival soft tissue only (peripheral variant).

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Cystic space containing desquamated keratin.
  • Thin parakeratinized epithelium lining about 6-10 cells thick.
  • Wavy corrugated surface.
  • Prominent palisaded, cuboidal to low-columnar basal cell layer. 
  • High mitotic activity.

You differential diagnosis should include:

  • Odontogenic cysts (dentigerous, radicular, lateral periodontal, glandular odontogenic).
  • Nonodontogenic cyst (nasopalatine duct).
  • Odontogenic tumors (ameloblastoma, myxoma).
  • Giant cell granuloma.

Due to the elevated risk of recurrence (10-30%), treatment tends to be more aggressive than comparable cysts. Treatment options include:

  • Enucleation.
  • Cryotherapy.
  • Marsupialisation and decompression.
  • Marginal or segmental resection.

RADICULAR CYST

Radicular Cysts are the most common inflammatory odontogenic cysts derived from epithelial remnants of the periodontal ligament (Malassez’s rest) that are triggered by pulpal necrosis. The resulting cyst is preceded by a periapical granuloma and mostly involves the apex of the affected tooth. The common clinical presentation includes:

  • Well-defined round radiolucency with a sclerotic margin.
  • Linked to root apex or lateral to root surface (lateral canal) of a necrotic tooth.
  • Asymptomatic unless there is an acute exacerbation (infection).
  • Generally a small slow growing cyst.
  • Root resorption is uncommon.

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Cystic cavity is lined by nonkeratinized stratified squamous epithelium.
  • Lumen filled with cell debris, fluid, cholesterol. 
  • Connective tissue wall with mixed inflammatory infiltrate.
  • Rushton bodies are occasionally observed (keratin-like products of odontogenic epithelium).

Treatment options include:

  • Endodontic therapy.
  • Tooth extraction and cyst removal.
  • Periapical surgery (marsupialisation, enucleation).

THYROGLOSSAL DUCT CYST

Thyroglossal Duct Cysts are derived from the embryological remnants of the thyroglossal duct, and can form anywhere along the thyroid’s route of migration from the tongue base (foramen cecum) to the thyroid’s location in the neck. They are largely a pediatric mass but may be present in adults. The common clinical presentation includes:

  • Soft, painless, slow growing mass in the anterior midline of the neck of children and young adults.
  • Ultrasound examination usually reveals a unilocular lesion.
  • Closely associated with the hyoid bone (most above the hyoid).
  • May involve the tongue.

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Cyst lined with respiratory (ciliated columnar) or squamous epithelium.
  • The cyst wall may contain residual thyroid tissue.
  • Can become infected, in which case inflammatory infiltrates present.
  • Granulation tissue or giant cells.

Your differential diagnosis should include:

  • Lingual thyroid.
  • Lingual carcinoma.
  • Dermoid or epidermoid cysts.
  • Lingual salivary tumor.
  • Thyroid carcinoma or squamous cell carcinomas.

Treatment usually involves surgical excision.

TRAUMATIC BONE CYST

Traumatic Bone Cyst (solitary bone cyst, hemorrhagic bone cyst, extravasation cyst, simple bone cyst) is an uncommon non-epithelial lined, non-neoplastic intraosseous cavity that lacks a clear etiology or pathogenesis. It may be caused by traumatic injury producing intramedullary hemorrhage and subsequent clot resorption, or perhaps degeneration of another (primary) intrabony pathology. Lesions are generally asymptomatic and discovered incidentally through routine radiographic examination. The common clinical presentation includes:

  • Clearly defined unilocular radiolucency.
  • Well-defined border that may extend between tooth roots (scalloped pattern).
  • Asymptomatic, though can present with pain, swelling, or tooth sensitivity.
  • May cause root resorption, paresthesia, bony expansion, or delayed eruption.
  • Usually involves the body of the mandible.

Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:

  • Empty bony space (pseudocyst).
  • Lack of epithelial lining. Collagen and fibrin line the dead space.
  • Lamellar bone seen along margins.

Your differential diagnosis should include:

  • Hemangioma.
  • Apical periodontitis/abscess.
  • Odontogenic keratocyst.
  • Giant cell granuloma.
  • Ameloblastoma.
  • Neurogenic neoplasms.

Treatment usually involves surgical exploration and careful curettage. 

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