Aggressive reactive periostitis (ECR 2010 Case of the Day)

Clinical History

41-year-old female violin player came with swelling and pain of her 4th finger.

Imaging Findings

Plain film manifested soft tissue swelling in the 4th finger; as well as increased density, calcifications and paraosteal-periosteal reaction of the lateral proximal phalanx (Fig. 1).
US showed calcified soft tissue mass on the transverse and longitudinal plane (Fig. 2).
On MRI an ill defined soft tissue mass was demonstrated on the volar and ulnar side of the proximal phalanx, paraosteal-periosteal irregular heterotopic calcifications were shown and intense soft tissue oedema surrounded the lesion. The cortex was intact and there was no continuity with bone marrow. On FSE T1wi lesion was iso or slightly hyperintense to muscle (Fig. 3), on fat-suppressed FSE the lesion was hyperintense (Fig. 4) and gradient echo nicely demonstrated lamellated irregular periosteal calcify mass (Fig. 5). Strong enhancement was seen after gadolinium injection (Fig. 6).
MDCT confirmed the calcifying periosteal mass proliferation without cortical involvement (Fig. 7).

Discussion

Florid reactive periostitis is an uncommon bone lesion that most often occurs in the long tubular bones of the hands and feet. It is also known as Nora’s lesion, aggressive florid periostitis or bizarre osteochondromatous proliferation (BPOP). Is part of the spectrum of reactive lesions including florid reactive periostitis and turret exostosis.
Clinically patients present with finger swelling, moderate pain and erythema associated with minimal trauma.
Its high incidence in the right hand and the predominant location on the proximal phalanx suggest traumatic or micro-trauma origin.
Radiological appearance shows bone proliferation hetero-topic ossification adjacent to the cortical bone lacking continuity with the underlying bone marrow and with intact cortex and soft tissue changes.
Pathological studies have demonstrated three different stages starting with reactive periostitis with minimal osteocartilaginous proliferation. It is followed by bone and metaplastic cartilage formation, and ends with mature ossification and cartilage cap. Radiologically these different stages can be also followed from a subtle soft tissue calcify periosteal mass to a sessile bone formation.
Its distinct radiological features allow differential diagnosis with bone tumours such as paraosteal osteosarcoma or chondrosarcoma and biopsy is usually not needed.

Differential Diagnosis List

Final Diagnosis

Aggressive reactive periostitis

URL:	https://www.eurorad.org/case/8960
DOI:	10.1594/EURORAD/CASE.8960
ISSN:	1563-4086