Bone tumours mnemonic

Radiological signs of malignant bone tumours

The mnemonic

Sun, Triangle, Onion

What each word stands for

  • SunSunburst periosteal reaction (osteosarcoma)
  • TriangleCodman's triangle (osteosarcoma, also other aggressive lesions)
  • OnionOnion-peel periosteal reaction (Ewing sarcoma)

Why it matters clinically

A frequent image-based question; each sign suggests an aggressive lesion.

Where it stops being reliable

Signs are not specific, because Codman's triangle and sunburst also occur in infection and other tumours.

Teaching aid, still awaiting independent review. Confirm facts in a standard source.

More mnemonics

Common questions

What is the Bone tumours mnemonic?

Sun, Triangle, Onion. It helps you recall: Radiological signs of malignant bone tumours.

What does "Sun" stand for?

Sunburst periosteal reaction (osteosarcoma)

What does "Triangle" stand for?

Codman's triangle (osteosarcoma, also other aggressive lesions)

What does "Onion" stand for?

Onion-peel periosteal reaction (Ewing sarcoma)

What are all the parts of the Sun, Triangle, Onion mnemonic?

Sun: Sunburst periosteal reaction (osteosarcoma); Triangle: Codman's triangle (osteosarcoma, also other aggressive lesions); Onion: Onion-peel periosteal reaction (Ewing sarcoma).

Which topic does this mnemonic belong to?

It belongs to Bone tumours in Orthopaedics.

Where does this mnemonic stop being reliable?

Signs are not specific, because Codman's triangle and sunburst also occur in infection and other tumours.

How is this useful clinically?

A frequent image-based question; each sign suggests an aggressive lesion.

How do I make this mnemonic stick?

Say it aloud, write it from memory tomorrow, then again in a week. Then test yourself on a Orthopaedics question about Bone tumours.

Is this a standard mnemonic?

It is a teaching aid written or adapted by our team. Some resemble ones students share informally. Check any fact that matters in a standard source.