<< backWHO classification: Odontogenic epithelial tumours without odontogenic ectomesenchyme
The following tumours belong to this group:
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Ameloblastoma
Synonyms: Adamantinoma, epithelial odontoma, adamantoblastoma, multilocular cys
Definition and clinical picture
Ameloblastoma is the most frequent odontogenic tumour (18%). Development from epithelial rests on the dental ridge and cell rests of Malassez, as well as the enamel organ; may also develop from an odontogenic cyst (follicular cyst, calcifying odontogenic cyst or keratocyst). No predilection for either sex; occurs mainly between the third and fourth decades of life. Occurs extremely rarely before the age of 18. Location: >75% of cases in the mandible, 50% of which occur in the molar and premolar regions. Histologically, this is a benign tumour; clinically, however, it is semi-malignant due to locally extremely aggressive infiltrating growth into marrow spaces; it tends to recur but hardly ever develops metastases.
Clinical features: Asymptomatic swelling, rarely loosening of teeth, pain or inflammation.
Malignant ameloblastoma, an odontogenic carcinoma, is very rare. Formation of metastasis in regional lymph nodes without significant changes to the underlying structure in the primary tumour.
Diagnosis / Histological findings
Radiology: Not pathognomonic; typically, unilocular or multilocular bubble-type or honeycomb-like osteolysis occurs. Root resorption, tooth displacement, and sometimes teeth within the lesion are possible.
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Histology: Three main growth forms and variants without particular therapeutic or prognostic significance:
- Follicular type
- Plexiform type
- Unicystic type (in younger patients)
- luminal
- intracystic
- mural
- Cellular variants with squamous epithelium (acanthomatous) metaplasia, granular cell metaplasia and basal cell metaplasia. Rarely: desmoplastic ameloblastoma with increased cellularity and less aggressive in the anterior maxilla.
- Extra-osseous occurrence in the oral mucosa (peripheral ameloblastoma); in older patients the tendency to recur decreases.
Histological criteria for diagnosis:
- Tumour cell compounds consisting of highly prismatic ameloblastoma cells
- Peripheral palisade structure,
- Subnuclear vacuoles
- No formation of hard tissue
- No proliferating stroma component
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Differential diagnosis
- Ameloblastic fibroma
- Adenomatoid odontogenic tumour
- Odontogenic squamous cell tumour
- Calcifying epithelial odontogenic tumour (Pindborg)
- Giant cell granuloma
- Carcinoma metastasis
Treatment and prognosis
- Local, radical resection with a safety distance of at least 0.5 cm exceeding the macroscopic margin of the tumour
- Immediate reconstruction, or
- Bilateral primary reconstruction once the final histological diagnosis is made
Tendency to recur: up to 30% (approx.). Since approx. 50% of relapses occur within the first 5 years, follow-up is recommended for at least 10 years (initially more frequent, then annual, clinical and radiological control)
back upSquamous odontogenic tumour
Definition and clinical picture
This is a benign, locally invasive tumour consisting of complexes from mature squamous epithelium that are embedded in fibrous stroma. It occurs very rarely; adults are usually affected in their third decade; no predilection for either sex
Diagnosis / Histological findings
Radiological findings: Well-demarcated unilocular radioluceny
Histology: Lines and islets of differentiated squamous epithelium in stroma with only a few cells. No palisade structure of the basal cell layer, no atypia. Possibly degenerative cyst formation, calcification. Occasionally variants with light cells.
Differential diagnosis
Ameloblastoma
Primary intra-osseous squamous cell carcinoma
Treatment and prognosis
Excision
Occasional recurrence, individual blastomas are aggressive (wrong diagnosis?)
back upCalcifying epithelial odontogenic tumour
Synonym: Pindborg tumou
Definition and clinical picture
A very rare, locally aggressive though benign epithelial tumour with amyloid deposits that may calcify. It occurs between the ages of 30 and 60, with no predilection for either sex. Location: 60% in the mandible, 30% in the maxilla; it occurs most frequently in the premolar region and is often associated with an impacted tooth. Rarely also extra-osseous. Clinically: usually asymptomatic swelling, often only detected on the radiograph by calcified shadows
Diagnosis / Histological findings
Radiology: Well defined osteolysis, often around the crown of an impacted molar. Large foci may appear multilobular.
Histology: The tumour consists of islets and rows of small odontogenic epithelia in stroma with few cells. The epithelial cells are often clearly pleomorphic, sometimes they are multinucleate, with mitosis being rare. Foci of calcification, varying in size, and intra-cellular and extra-cellular amyloid deposits with surrounding foreign-body reaction and formation of granulation tissue.
Differential diagnosis
Calcifying odontogenic cyst
Odontogenic fibroma
Carcinoma metastasis
Treatment and prognosis
Very wide excision; long-term follow up
Recurs only rarely
back upClear-cell odontogenic tumour
Definition and clinical picture
Clear-cell odontogenic tumours are rare, locally invasive odontogenic tumours. They occur between the fifth and seventh decades of life, with a prevalence in women, and mostly in the mandible. Locally, they show more aggressive growth than ameloblastoma
Diagnosis / Histological findings
Histology: Complexes of islet-type uniform vacuolised cells with light cytoplasma (glycogen) of varying size. Only sparse fibrous stroma
Differential diagnosis
Clear-cell adenoma
Clear-cell odontogenic carcinoma
Treatment and prognosis
Segmental resection (as with ameloblastoma)
High rate of recurrence
Long post-operative follow-up
back upsources
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Horch, H. H.
(o.J.)
Mund-Kiefer-Gesichtschirurgie 1
Praxis der Zahnheilkunde 10,1
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Morgenroth K, Philippou S
(1998)
Oralpathologie II; Zahnsystem und Kiefer in der Reihe von Spezielle pathologische Anatomie
Springer, Berlin - Heidelberg - New York
-
Philipsen HP, Reichart PA
(1998)
Unicystic ameloblastoma. A review of 193 cases from the literature
Oral Oncol. 1998 Sep;34(5):317-25
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Philipsen HP, Reichart PA, Nikai H, Takata T, Kudo Y
(2001)
Peripheral ameloblastoma: biological profile based on 160 cases from the literature
Oral Oncol. 2001 Jan;37(1):17-27
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Pindborg JJ
(1958)
A calcifying epithelial odontogenic tumour
Cancer. 1958 Jul-Aug;11(4):838-43
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Reichart PA, Philipsen HP
(1999)
Oralpathologie. Farbatlanten der Zahnmedizin 14
Georg Thieme Verlag, Stuttgart, New York
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Reichart PA, Philipsen HP, Sonner S
(1995)
Ameloblastoma: biological profile of 3677 cases
Eur J Cancer B Oral Oncol. 1995 Mar;31B(2):86-99
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