Geographical bony lesion Focal lesion ,well defined, rounded, lobulated or polygonal Can be divided to 3 sub types : IA: sclerotic margins denoting slowly progressive lesion (bone cyst ,NOF ,Fibrous dysplasia) IB: well defined ,non sclerotic margins ,denoting more rapid ,but still benign lesion (GCT, Chondromyxoid fibroma). IC :ill defined border denoting rapidly evoluting lesion (Malignant or infectious)
Moth eaten lesion Formed of small multiple bony lucencies destroying the cortex . Corresponds to either infectious or malignant lesion .
Permeative lesion Corticaldestruction by multiple bony lucencies ,seen in tangential view . Denoting a very aggressive process .. Either malignant or infectious.
Mixed processes Geographical osteolyis ,surrounded by dense sclerosis: Denotes slowly progressive lesion (osteoid osteoma,Osteoblastoma or chronic osteitis ) Complex ,disorganized lesion formed of lytic and sclerotic areas almost always with malignant or infectious pathologies
Periosteal reaction Periosteal agression by a bony lesion (or less frequently soft tissue lesion )leads to osteogenesis from subperiosteal osteoblasts . Manifested 2-4 weeks after beginning of the process.
:Types of periosteal reaction 1.Solid homogenous. 2.Remodelled reaction. 3.continuous-separate from the cortex(uni or multi-lamellar). 4.Spiculated reaction (sun ray..brush border) 5.discontinuous periosteal reaction.