Strands of odontogenic epithelium are embedded in mesenchyme with a myxoid appearance.
The mesenchyme is said to resemble dental papillae (embryonic dental pulp) of developing teeth.
Small islands and cords of odontogenic epithelium in a background of primitive mesendyme typifies ameloblastic fibroma.
Ameloblastic fibroma and fibro-odontomas are related neoplasms composed of odontogenic epithelium and mesenchyme; fibro-odontomas have the added component of dentin and enamel.
Histologically, ameloblastic fibromas are composed of cords, strands and islands of odontogenic epithelium embedded in a loose stroma that resembles dental pulp. The peripheral cells in the islands are basaloid and resemble ameloblasts whereas the central cells are looser, and resemble stellate reticulum. In ameloblastic fibrodentinomas, dysplastic dentin may be formed (Barnes). In ameloblastic fibro-odontomas, mineralized material (enamel, dentin) is present in the stroma (Thompson).
These are rare lesions most common in the first two decades of life. They are rare in adults. The posterior mandible is the most common location. They are usually asymptomatic, but larger neoplasms may present as a swelling or prevent eruption of teeth.
If managed by radical excision, the recurrence rate for ameoblastic fibromas is less than 10%; however, in conservative treatment, recurrence may be up to 90%. Less than 10% of cases may underog malignant transformation into a ameloblastic fibrosarcoma (Thompson).
In contrast, no recurrences in ameloblastic fibro-odontoma have been documented.
Barnes L, Eveson JW, Reichart P, Sidransky D. WHO Classification: Pathology and Genetics, Head and Neck Tumors Lyons, France: IARC; 2005: 308-309.
Thompson LDR, Wenig BM, eds. Diagnosis Pathology: Head and Neck. 1st Ed. Manitoba, Canada; Amirsys;2011; 6-48,49.