Fact-sheet: Bizarre paraosteal osteochondromatous proliferation - Nora
Updated on 09/05/2019 at 9:31 AM
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Definition
Evolving continuum between florid reactive periostitis, Nora's disease, and turret exostosis.
Rare pseudotumoral lesion, with no sex predominance.
Rare bone lesion most often located on the proximal or intermediate phalanges, metacarpals, and metatarsals
Clinical features
Painless swelling evolving over several months or years.
Pain or cutaneous erythema possible related to mass effect or mechanical issues.
History of trauma in 40% of cases.
Involvement of the hands is 4 times more common than that of the feet.
Even rarer involvement of the humerus or clavicle.
Peak incidence between 20 and 40 years.
Sex ratio=1.
5 to 30 mm.
Radiography
Partially ossified uni- or polylobulated lesion, sessile or pedunculated, well delineated, arising from the bone cortex, without modification of the cancellous bone, with characteristic topography.
Ultrasound
Noncontributory.
CT
Well-defined, partially calcified/ossified lesion, with characteristic topography.
No pathological infiltration of the soft tissues.
Possible scalloping of the adjacent cortex.
Cortical but not cancellous continuity, which differentiates this lesion from osteochondroma.
MRI
No specific signal on MRI.
Differentiation of the osseous and cartilaginous portions.
Contrast enhancement after gadolinium injection, with intramedullary edema, which may wrongly suggest a malignant evolving process.
Management
Surgical excision if symptomatic.
Recurrence possible after surgery (50% within 2 years).
Differential diagnosis
Subungueal exostosis.
Osteochondroma.
Chondrosarcoma.