Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Case Reports
. 2021 Dec;49(12):3000605211064390.
doi: 10.1177/03000605211064390.

Nora's lesion of the distal ulna: a case report

Cheng Han Lin  1 , Karl Wu  1   2
Affiliations
Case Reports

Nora's lesion of the distal ulna: a case report

Cheng Han Lin et al. J Int Med Res. 2021 Dec.

Abstract

Nora's lesion, also known as bizarre parosteal osteochondromatous proliferation (BPOP), is a very rare benign lesion with few published cases. BPOP is more common in adults during the second to third decades of life, and usually occurs on the hands and feet. Radiologically, it appears as a calcified mass attached to the bone cortex that grows rapidly and that recurs easily following resection. Aggressive features on imaging and confusing histopathological findings usually result in misdiagnosis or mistreatment. Herein, we present a case of a rare bony tumour involving the distal ulna presenting as a painless growing mass. An excisional biopsy with clear margins was performed without disturbing the ulnar nerve and arteries. There was no recurrent mass or calcified lesion 1 year after surgery. Based on its rarity and difficult diagnosis, BPOP should be considered in the differential diagnosis of a painless mass in the distal ulnar region. Careful follow-up after surgery is essential, even without lesion recurrence.

Keywords: Nora’s lesion; bizarre parosteal osteochondromatous proliferation; calcified mass; case report; distal ulna; excision; painless mass.

PubMed Disclaimer

Conflict of interest statement

Declaration of conflicting interest: The authors declare that there is no conflict of interest.

Figures

Figure 1.
Figure 1.
Pre-operative left wrist anteroposterior (AP) and lateral (LAT) views showing a calcified, ill-defined tumour on the volar side of the left ulna.
Figure 2.
Figure 2.
Pre-operative left wrist anteroposterior (AP) and lateral (LAT) views showing a calcified, ill-defined tumour on the volar side of the left ulna.
Figure 3.
Figure 3.
Pre-operative magnetic resonance (MRI), proton density-weighted image with fat suppression phase showing a left distal ulnar (wrist) volar ossified mass. Multiple calcified spots are visible within the tumour, which measured 3.0 × 1.8 × 1.3 cm. The volar cortex of the ulna, and the ulnar artery and nerve were intact.
Figure 4.
Figure 4.
Pre-operative magnetic resonance (MRI), proton density-weighted image with fat suppression phase showing a left distal ulnar (wrist) volar ossified mass. Multiple calcified spots are visible within the tumour, which measured 3.0 × 1.8 × 1.3 cm. The volar cortex of the ulna, and the ulnar artery and nerve were intact.
Figure 5.
Figure 5.
The well-encapsulated volar ulnar mass was resected.
Figure 6.
Figure 6.
The tumour was completely removed with an intact capsule.
Figure 7.
Figure 7.
Histological findings in our case. Low magnification (×40) haematoxylin and eosin staining (a and b) showing mature osseous tissue mixed with adipose tissue and a highly cellular cartilaginous cap (long arrows in b) with enlarged chondrocytes, mild atypia and irregular ossification. There are also interspersed regions of fibrovascular stroma with spindle cells (dashed arrow in a).
Figure 8.
Figure 8.
Histological findings in our case. Low magnification (×40) haematoxylin and eosin staining (a and b) showing mature osseous tissue mixed with adipose tissue and a highly cellular cartilaginous cap (long arrows in b) with enlarged chondrocytes, mild atypia and irregular ossification. There are also interspersed regions of fibrovascular stroma with spindle cells (dashed arrow in a).
Figure 9.
Figure 9.
Post-operative X-ray images of the left wrist, anteroposterior (AP) and lateral (LAT) views, showing no remnant mass or calcified areas.
Figure 10.
Figure 10.
Post-operative X-ray images of the left wrist, anteroposterior (AP) and lateral (LAT) views, showing no remnant mass or calcified areas.
See this image and copyright information in PMC

References

    1. Nora FE Dahlin DC andBeabout JW.. Bizarre parosteal osteochondromatous proliferations of the hands and feet. Am J Surg Pathol 1983; 7: 245–250. - PubMed
    1. Meneses MF Unni KK andSwee RG.. Bizarre parosteal osteochondromatous proliferation of bone (Nora’s lesion). Am J Surg Pathol 1993; 17: 691–697. - PubMed
    1. Soejima O andOgata TIK.. Case reports extensor pollicis longus tendon rupture caused by a bizarre parosteal osteochondromatous proliferation of the wrist. Hand Surg 1998; 3: 277–281.
    1. Michelsen H, Abramovici L, Steiner G, et al.. Bizarre parosteal osteochondromatous proliferation (Nora’s lesion) in the hand. J Hand Surg 2004; 29: 520–525. - PubMed
    1. Dhondt E, Oudenhoven L, Khan S, et al.. Nora’s lesion, a distinct radiological entity? Skeletal Rad 2006; 35: 497–502. - PubMed

Publication types

LinkOut - more resources