Everyone loves the bone tumors!

Describe it: multiloculated lytic defect with peripheral sclerotic rim located eccentrically in the metaphysis of a long bone. Only minimal cortical thickening without significant periosteal reaction. Does that help?

Answer: Non-ossifying fibroma (The lesion of many names: aka fibroxanthoma or if it’s <2cm fibrous cortical defect or benign cortical defect)

This is one of the so called “Don’t Touch lesions”. It is benign so don’t touch it (unless it has a pathological fracture, which it can). These are fairly common and are almost always incidental.

reference: https://radiopaedia.org/articles/non-ossifying-fibroma-1

or http://learningradiology.com/archives2009/COW%20344-Benign%20Cortical%20Defect/bcdcorrect.htm