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Pathology · patient case with 3 questions

Cortical Expansion of the Posterior Mandible

demo: 34-year-old male

chief: “The outside of my jaw has been slowly swelling for about a year.”

history: Non-contributory. No pain, no paresthesia.

meds: None

findings: Occlusal radiograph shows buccal and lingual cortical expansion in the posterior mandible. Panoramic view shows a multilocular soap-bubble radiolucency. Clinical images and radiographs shown below.

Case image

Question 1

Given the multilocular soap-bubble appearance with cortical expansion in the posterior mandible, which diagnosis is most likely?

  1. Simple bone cyst
  2. Condensing osteitis
  3. Ameloblastoma
  4. Periapical cemento-osseous dysplasia
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Correct answer: C. Ameloblastoma

  • A. A simple bone cyst produces a scalloped radiolucency between roots without expansion and with no lining.
  • B. Condensing osteitis is radiopaque, not radiolucent.
  • C. Correct. Ameloblastoma is a benign but locally aggressive odontogenic tumor with a strong predilection for the posterior mandible, producing multilocular soap-bubble or honeycomb radiolucency with marked cortical expansion and often root resorption.
  • D. Cemento-osseous dysplasia is a periapical mixed-density lesion of vital anterior mandibular teeth, without expansion.

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Question 2

Ameloblastic fibroma differs from ameloblastoma in which respect?

  1. It is a malignant tumor requiring radical resection with wide margins
  2. It occurs almost exclusively in the anterior maxilla of elderly patients
  3. It is composed purely of odontogenic epithelium with no mesenchymal component
  4. It is a mixed epithelial and mesenchymal tumor occurring in children and adolescents, with myxomatous connective tissue
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Correct answer: D. It is a mixed epithelial and mesenchymal tumor occurring in children and adolescents, with myxomatous connective tissue

  • A. It is benign; conservative surgical excision is the treatment.
  • B. It favors the posterior mandible in young patients, not the anterior maxilla of the elderly.
  • C. The mixed epithelial and mesenchymal composition is precisely what defines it.
  • D. Correct. Ameloblastic fibroma is a rare benign mixed tumor of children and teenagers, favoring the posterior mandible, with odontogenic epithelium set in myxomatous connective tissue. If an odontoma is also present it is called an ameloblastic fibro-odontoma. Treatment is surgical excision.

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Question 3

Central ossifying fibroma is best distinguished from its peripheral counterpart by which feature?

  1. The central form occurs in the gingiva; the peripheral form occurs in bone
  2. The central form occurs within bone with a well-circumscribed radiolucency containing central ossification; the peripheral form occurs in the gingiva with no radiolucency or radiopacity
  3. The central form requires no treatment while the peripheral form requires resection
  4. Only the peripheral form has a juvenile aggressive variant
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Correct answer: B. The central form occurs within bone with a well-circumscribed radiolucency containing central ossification; the peripheral form occurs in the gingiva with no radiolucency or radiopacity

  • A. This reverses the definitions.
  • B. Correct. The central lesion sits within bone, typically between the premolar and molar regions of the mandible, as a well-circumscribed radiolucency with ossified product in the centre — similar in appearance to cementifying fibroma. The peripheral lesion is a soft tissue gingival mass with no radiographic bony change.
  • C. Both forms are treated by surgical excision.
  • D. The juvenile aggressive variant, with rapid growth, is described for the central lesion.

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