True about Ameloblastoma: (PGI Dec 2006)

Ans: A (Cystic lesion) Adamantinoma or Admantine Epithelioma or Ameloblastoma# It is an epithelial tumor arising from ameloblast (enamel forming cell).# It's most common site is posterior mandible in the area of molar teeth\It commonly presents in 3rd to 5th decades of life.It is a slow growing, locally invasive cystic benign tumor7 that causes expansion of outer table more than inner table of mandible. Cystic degeneration may l/t softening & egg shell cracking on palpation.It rarely metastasize and l/t honey comb/ bubbly appearance on x-ray. Wider section of tumor is treatment of choice. Chemo & radiotherapy has no roleApart from mandible, it is almost exclusively found in tibial diaphysis7 Late metastases to inguinal nodes & lung can rarely occurMost common bone tumor of mandible is ameloblastomaQ but mot common tumorofja tvissaguomous cell carcinom a arising from oral mucosa over mandible.Also remember:Bone tumorMost common siteUnicameral / Solitary' / Simple Bone cystQMetaphysis of proximal humerusQ > femurAneurysmal Bone cystQFemur & tibiaEnchondromaQMetaphysis of small bone of handsQ (& feet)Osteochondroma (Exostosis, m.e benign bone tumorQDistal femur > upper tibia > proximal humerusOsteoid osteomaFemur > tibia (diaphysis)OsteosarcomaDistal femur > Upper tibiaQ (metaphysis)Ewing's sarcomaQFemur > Tibia (diaphysis)Fibrous dysplasiaQUpper end femur (22%) > Tibia (21%) > Lower femur (12%)ChordomaQSacrum (most common)Q > sphenooccipital region (clivus) Q > anterior vertebral bodyQ i.e. involves only axial skeletonQIvory osteomaFrontal sinusQAdamantinomaMandibleMultiple myelomaVertebraeQ