Lucent bone lesions
Well-defined, sclerotic margin
- 1. Nonossifying fibroma —young patients, eccentric metaphyseal location. Consider benign fibrous histiocytoma if patient >25 years or atypical location.
- 2. Bone cysts — both SBCs and ABCs usually have a thin sclerotic margin. ABCs are more eccentric and expansile.
- 3. Fibrous dysplasia — variable appearance, typically diaphyseal.
- 4. Chondroblastoma —epiphyseal location, young patients. If patient >20 years, consider clear cell chondrosarcoma.
- 5. Brodie’s abscess —typically young patients, most common in metaphysis. Discrete lucency with surrounding ill-defined sclerosis.
- 6. Healing metastases or primary malignant bone lesions — sclerotic rim indicates a good response to treatment.
- 7. Osteoblastoma — large lucent nidus with a sclerotic margin. Most common in spine.
- 8. Intraosseous lipoma — typically in calcaneus or intertrochanteric region of femur. Thin sclerotic margin. Focus of central calcification is pathognomonic but not always present.
- 9. Liposclerosing myxofibrous tumour — characteristic location: intertrochanteric region of femur. Usually a thick sclerotic margin.
- 10. Adamantinoma/osteofibrous dysplasia (OFD) — characteristic location: anterior cortex of tibial diaphysis. Both can look identical but OFD occurs in a younger age group (<10 years).
- 11. Chondromyxoid fibroma— rare; can mimic NOF, BFH and ABC.
- 12. Haemophilic pseudotumour— usually very expansile + other signs of haemophilia.
Well-defined, nonsclerotic margin
- 1. Metastasis — usually older patients, in axial or proximal appendicular skeleton.
- 2. Myeloma/plasmacytoma —older patients, usually in axial or proximal appendicular skeleton. Typically ‘punched-out’ appearance, may be expansile.
- 3. Low-grade chondral lesions —e.g. enchondroma, low-grade chondrosarcoma. Both can be lytic without chondroid matrix.
- 4. Giant cell tumour —typically has a well-defined nonsclerotic margin. Adults 20–50 years.
- 5. Simple/aneurysmal bone cyst —both may have no perceptible sclerotic margin.
- 6. Eosinophilic granuloma —may appear well-defined.
- 7. Brown tumour —often expansile. Look for other signs of hyperparathyroidism.
- 8. Lytic phase of Paget’s disease —well-defined flame-shaped advancing edge without sclerosis.
- 9. Desmoplastic fibroma —rare. Often contains pseudotrabeculations.
Poorly defined margin
- 1. Metastasis —usually ill-defined.
- 2. Myeloma —usually discrete but may appear ill-defined.
- 3. Osteomyelitis —ill-defined and lytic in the acute phase.
- 4. Bone lymphoma — typically ill-defined subtle bone destruction with a large soft tissue mass. Can occur at any age but more common in older patients.
- 5. Primary bone sarcomas —e.g. Ewing sarcoma, osteosarcoma, chondrosarcoma, fibrosarcoma, undifferentiated pleomorphic sarcoma, angiosarcoma. Internal matrix may be absent.
- 6. Eosinophilic granuloma —patients <30 years. Can occur anywhere, often has an aggressive appearance indistinguishable from infection or malignancy.
- 7. Giant cell tumour —can appear ill-defined. Adults 20–50 years.