Ameloblastic Fibroma — MFDS Part 1 MCQ

Correct answer: C — Odontogenic epithelium within primitive dental-papilla-like ectomesenchyme, usually presenting in the first two decades

Ameloblastic fibroma is a benign mixed odontogenic tumour composed of odontogenic epithelial strands or islands within primitive, dental-papilla-like ectomesenchyme. It most often presents during the first two decades, whereas conventional ameloblastoma is an epithelial odontogenic tumour that generally presents later. Option D therefore better describes ameloblastoma. A purely ectomesenchymal lesion without odontogenic epithelium, as in C, suggests a mesenchymal odontogenic tumour such as odontogenic myxoma. Formation of enamel and dentine in D points towards a developing odontoma or an ameloblastic fibro-odontoma-type lesion rather than a conventional ameloblastic fibroma. Malignant transformation of the mesenchymal component produces ameloblastic fibrosarcoma, described in E, and is not a defining feature of benign ameloblastic fibroma.

Reference: Vered M, Wright JM. Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Odontogenic and Maxillofacial Bone Tumours, Figure 2. Head and Neck Pathology. 2022;16:63–75. https://pubmed.ncbi.nlm.nih.gov/35312978/