bizarre parosteale osteochondromatöse Proliferation der Hand und der Finger

Lesions

involving the outer surface of the bone in children: a pictorial review. A 5-year-old boy with bizarre parosteal osteochondromatous proliferation at the middle phalanx of the right index finger. Antero-posterior radiograph of the right index finger a demonstrates a well-defined mass with amorphous calcifications (arrow) adjacent to the otherwise intact cortical surface of the middle phalanx. No medullary continuity is demonstrated between the lesion and underlying bone. Axial T1 post-contrast image b shows irregular peripheral contrast enhancement of the lesion without surrounding soft-tissue invasion (arrow). The lesion is hypointense on coronal T1 c and mostly hyperintense with few hypointense foci on axial T2 d (black arrow)

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Bizarre

parosteal osteochondromatous proliferation • Bizarre parosteal osteochondromatous proliferation (Nora lesion) - Ganzer Fall bei Radiopaedia

Skalski, M. Bizarre parosteal osteochondromatous proliferation (Nora lesion). Case study, Radiopaedia.org. (accessed on 21 Oct 2022) https://doi.org/10.53347/rID-30785 • CC by-nc-sa 3.0 (modified)

Pseudotumoural

soft tissue lesions of the hand and wrist: a pictorial review. Bizarre parosteal osteochondromatous proliferation (Nora’s lesion). a Plain radiograph of the finger showing a turret exostosis at the dorsal aspect of the proximal phalanx of the second finger (arrowhead). b Longitudinal ultrasound shows the exostosis causing focal contour deformity of the cortical bone (arrowheads) with adjacent hypoechoic cartilage cap (callipers)

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bizarre parosteale osteochondromatöse Proliferation der Hand und der Finger

bizarre parosteale osteochondromatöse Proliferation Radiopaedia • CC-by-nc-sa 3.0 • de

Bizarre parosteal osteochondromatous proliferations (BPOP), also known as Nora lesions, are benign exophytic osteochondral lesions which have an appearance similar to an osteochondroma and are typically seen in the hands and feet. On imaging, BPOPs are shown to be continuous with the underlying cortex, but usually without continuation of the medulla.

Epidemiology

They are most often seen in young (20-30-year-old) patients. There is no recognized gender predilection.

Radiographic features

Plain radiograph

Typically seen as a well-marginated wide-based bony growth projecting into the soft tissues although often lacks the characteristic orientation away from the nearby physis seen with osteochondromas. The mineralizing exophytic lesion arises from the cortical bone with or without osteolysis, cortical flaring or a periosteal reaction. A lack of medullary involvement is characteristic of bizarre parosteal osteochondromatous proliferation, although radiographic features alone cannot reliably diagnose the lesion.

Treatment and prognosis

Bizarre parosteal osteochondromatous proliferations are benign lesions with no risk of distant metastasis but they may show marked local invasion and may recur after surgical excision.

History and etymology

Frederick E Nora (fl. 2020) is an American pathologist who first described bizarre parosteal osteochondromatous proliferations whilst working at the Mayo Clinic in 1983 .