Bizarre Parosteal Osteochondromatous Proliferation (Nora Lesion): A Narrative Review

Attritional rupture of the extensor pollicis longus tendon secondary to an osteochondroma of the distal radius

The extensor pollicis longus (EPL) tendon, given its complex anatomical course, is at a higher risk of rupture when compared with other extensor tendons of the hand. This is most often seen in the trauma setting, and up to 60% of cases are related to an underlying distal radius fracture. Spontaneous atraumatic ruptures are uncommon and often attributable to prolonged steroid use and tenosynovitis.Attritional ruptures from osseous lesions of the distal radius are not well described, and we are unaware of any cases related specifically to distal radius osteochondroma. This may be due to the rare nature of osteochondroma in this region and the fact that many cases are asymptomatic in the absence of complications. This case illustrates spontaneous EPL rupture secondary to an osteochondroma of Lister's tubercle and highlights that excision and tendon transfer can safely be completed in the same operative setting.

Bizarre parosteal osteocondromatous proliferation (BPOP) of the acromion with soft tissue recurrence

Bizarre parosteal osteochondromatous proliferation (BPOP) is a benign but rare periosteal-originating chondrogenic tumor. It commonly arises from the hands and feet. It is slow-growing and often presents as a painless lump. On imaging, the mass is well-marginated and almost always remains contiguous with the cortical bone. Histologically, the lesion is composed of a disorganized admixture of fibrous tissue, bone, and cartilage with bizarre features. Treatment is surgical and local recurrence is common contiguous with bone. This case report demonstrates an uncommon acromial BPOP with the first reported recurrence not contiguous with the underlying cortex.

A unique presentation of the rare Nora's lesion, symptomatic bizarre parosteal osteochondromatous proliferation: A case report

Bizarre parosteal osteochondromatous proliferations, also known as Nora's lesions, are rare benign tumors with a high recurrence rate. They are often difficult to identify because of their similar appearance to other tumors. We describe a 25-year-old healthy female patient with bizarre parosteal osteochondromatous proliferations in an uncommon location on the pelvic ilium, presenting with unique clinical findings of abdominal pain and femoral paresthesia and showing atypical radiographic findings. To the best of our knowledge, this is one of the very few cases ever reported in the literature of Nora's lesion in this particular location and possibly the first case ever with this specific presentation. The lesions' radiographic images, combined orthopedic and general surgery procedures, and histological analysis are detailed. The patient's continued 4-year follow-up has demonstrated no symptoms or evidence of recurrence.

Bizarre Parosteal Osteochondromatous Proliferation of the Hand: A Report of an Atypical Case and Current Concepts

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora's lesion, is an unusual, benign, bony lesion often found in the tubular small bones of the hand and foot. In general, two characteristic radiological signs are used to diagnose the lesion, namely, (1) the absence of corticomedullar continuity and (2) BPOP developed from the parosteal surface of bones with an intact underlying cortex. Here, we present an atypical case of Nora's lesion of the proximal phalanx of the index finger, in which BPOP was diagnosed only histologically, with preoperative imaging examinations (X-ray and MRI) suggesting another lesion (enchondroma). Therefore, imaging (X-ray and MRI) alone may be inadequate to achieve the correct diagnosis of the lesion because many cartilaginous neoplasms may surround a broad range of lesions that mimic BPOP. Only histopathological evidence can confirm the correct diagnosis of the lesion.

Rare Case of Bizarre Parosteal Osteochondromatous Proliferation of Foot

INTRODUCTION

Nora's lesion or bizarre parosteal osteochondromatous proliferation (BPOP) is a rare, benign lesion of small bones of hands and feet in adults. It composed of differing amounts of cartilage, bone, and spindle cells and an unusual form of calcified cartilage so-called "blue bone".

CASE REPORT

A 23-year-old male presented with swelling at the lateral side of the fifth toe of his right foot, which was separated from the adjacent toe. Radiographs showed a mass arising from the proximal phalanx of the little toe, with no medullary and cortical continuity. Excisional biopsy of the mass was performed, and a histologic diagnosis of BPOP of bone (Nora's lesion) was made.

CONCLUSION

This case presented with a cartilaginous cap around tumor which is suggestive for benign nature of this tumor with some histological variation from bizarre variant along with no recurrence which is unlikely seen in BPOP.