History: knee pain, trauma
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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.