Ameloblastoma

Ameloblastomas, also known as adamantinoma, are the most common odontogenic tumor (35%). They are benign, locally aggressive neoplasms arising from ameloblasts, which typically occur at the angle of the mandible and are often associated with an unerupted tooth and must therefore be differentiated from a dentigerous cyst which will be centered around the crown. When in the maxilla (less common) they are located in the premolar region, and can extend up in the maxillary sinus.
They are classically multilocualted (80%), expansile bubbly lesions, with well demarcated borders and no matrix calcification.
Smaller lesions may demonstrate a characteristic enhancing mural nodule, best seen on MRI. Larger lesions have more prominent enhancing soft tissue.
Malignant degeneration into ameloblastic carcinoma or malignant ameloblastoma is rare.
For differential of ameloblastomas and a CT of the same patient please visit Radiopaedia.org here.
Reference:
1. StatDx.com
Credit: Dr Frank Gaillard
http://www.radpod.org