Mandible / maxilla
Odontogenic cysts
Periapical (radicular) cyst

Author: Annie Morrison, M.D. (see Authors page)
Editor: Kelly R. Magliocca, D.D.S., M.P.H.

Revised: 21 June 2018, last major update March 2014

Copyright: (c) 2004-2018, PathologyOutlines.com, Inc.

PubMed Search: Periapical (radicular) cyst [title]

Cite this page: Morrison, A. Odontogenic cysts: periapical (radicular) cyst. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/mandiblemaxillaperiapicalcyst.html. Accessed September 22nd, 2018.
Definition / general
  • Inflammatory odontogenic cyst
  • Lined by epithelial cells derived from rests of Malassez
  • Also called radicular cyst, apical periodontal cyst, root end cyst, or dental cyst
Terminology
  • Epithelial rest of Malassez:
    • Derived from Hertwig epithelial root sheath
    • Small spherules of 6 - 8 epithelial cells with high nuclear to cytoplasmic ratio
    • Little or no reverse polarity of cells
  • Periapical cyst: present at root apex
  • Lateral radicular cyst: present at the opening of lateral accessory root canals
  • Residual cyst: remains even after extraction of offending tooth
  • Periapical granuloma: chronic granulomatous inflammation of periapical tissues
Epidemiology
  • Most common odontogenic cyst (52% of jaw cystic lesions)
  • Most common in 4th & 5th decades, but occurs over wide age range
Sites
  • 60% in maxilla (vs. mandible)
  • Most commonly in apex of lateral incisors, but also along lateral accessory root canals
Pathophysiology
  • Dental caries or trauma cause chronic inflammation which eventually forms a periapical inflammation; continued inflammation stimulates cells of the rests of Malassez, the epithelial cells undergo necrosis to form the cyst which may be sterile or become secondarily infected
  • While most are lined by epithelium derived from rests of Malassez, epithelial lining may be respiratory type derived from the maxillary sinus, in the setting of a periapical lesion communicating with the sinus wall
  • May be oral epithelium from a fistula or oral epithelium proliferating down a periodontal pocket
Clinical features
  • May be asymptomatic and incidentally found with radiographs
  • Possible swelling (occurs slowly)
  • May be painful if infected
Radiology description
  • Round to oval radiolucency, often with well defined cortical border (this border can be lost when infected)
  • Can displace or reabsorb roots of adjacent teeth if large
Radiology images

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Radicular cyst

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Radicular cyst, root partially reabsorbed

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Upper maxilla

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Periapical cyst involving maxillary anteriors

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Progressive involution of periapical lesion

Prognostic factors
  • Dependent on tooth affected, size of cyst / extent of bone destruction and accessibility for treatment
  • Rare complications:
    • Squamous cell carcinoma and epidermoid carcinoma may arise from the epithelial lining of periapical cysts
    • Pathologic bone fracture (occurs with large cysts that erode nearly completely through the jaw)
Case reports
Treatment
  • In adult teeth, can treat necrotic pulp (infection source) via pulpectomy ("root canal") with sparing of the tooth; this induces involution of the cyst; can also extract tooth
  • In some very large cysts, after above treatment, additional surgical management (enucleation or marsupialization) is required for the osseous cyst
Clinical images

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Palatal swelling

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Lateral mandibular lesion

Gross description
  • Usually attached to tooth root, may be firm or have deflated capsule, lumen can contain thin serous or straw colored fluid, opaque yellow-white debris, muddy brown fluid from old hemorrhage or frank purulent debris
Microscopic (histologic) description
  • Lined by stratified squamous epithelium of variable thickness, often with scattered ciliated cells
  • Exception is when epithelium is derived from maxillary sinus and thus lined with respiratory epithelium (pseudostratified ciliated columnar epithelium), may have acute inflammatory cell infiltrate
  • Rushton hyaline bodies: amorphic, eosinophilic, linear to crescent shaped bodies, found in epithelium of 10% of periapical cysts
  • Fibrous capsule: varying thickness with chronic inflammatory cells, plasma cells may be particularly prominent
  • Cholesterol clefts are common within cyst lining
Microscopic (histologic) images

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H&E

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Cyst

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H&E

Differential diagnosis
  • Influenced by degree of inflammation, anatomic location of cyst, amount of cystic epithelium present (incisional biopsy vs complete enucleation)
  • Inflamed developmental odontogenic cyst
  • Periapical granuloma
  • Surgical ciliated cyst
  • Traumatic bone cyst
Additional references