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Table 2 Painful OO’s differential diagnoses main imaging findings

From: Osteoid osteoma: the great mimicker

Differential diagnoses Key points
Osteomyelitis/intraosseous abscess Uneven inner margin; irregularly shaped and eccentrically located sequestrum; usually intramedullary located and larger than 2.0 cm; does not enhance in its central portion; penumbra sign may be present
Fracture/stress reaction Fracture line may be present; lack of a nidus; Follow-up imaging can be helpful in doubtful cases because the bone marrow edema regress over time and the fracture consolidates
Osteoblastoma Larger than 2.0 cm; less painful; fewer inflammatory changes and reactive sclerosis; smaller response to salicylates; grow progressively; malignant potential and may be associated with other tumors
Glomus tumor Well-defined nodule in the nail bed; no thickening of the rest of the nail bed or matrix; may exhibit well-defined remodeling of the dorsal cortical of the distal phalanx
Chondroblastoma Epiphyseal intramedullary location; lobulated contours; larger dimensions; chondral calcifications and signal intensity