OSTEOSARCOMA

HALLMARK FEATURES:
      • Destructive lesion
      • Bone formation in matrix
      • Around knee

Metaphyseal
Agressive
destructive
Cortical destruction
matrix ossification (cloud like rather than whorled)
Periosteal reaction
Soft tissue mass


PAROSTEAL OSTEOSARCOMA

HALLMARK FEATURES:
      • Denser bone extending from periosteum
      • Around knee
      • Especially posterior femur

Lucent areas in dense bone
Lucent interface in 1/5 only

PERIOSTEAL OSTEOSARCOMA

HALLMARK FEATURES:
      • Saucerisation
      • New bone
      • Think of it !

Saucerisation on surface
Lucent
Radiating bone spicules
Density increases towards centre
Thick underlying cortex

TELANGIECTATIC OS

HALLMARK FEATURES:
      • Expansile
      • Mimics ABC but fewer fluid levels
      • Mimics hydatic cyst

Telangectatic variant

More geographic, sharp margins
Expansile
Radiolucent matrix
Septations and fluid levels, though not >70% like ABC