Fibrosarcoma in bizarre parosteal osteochondromatous proliferation

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

Background

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora lesion, is a rare proliferative disease arising from the parosteal region of bones. Although BPOP's pathogenesis is still not certain, modern literature suggests it to be a tumor-like lesion or even a benign neoplasm. Due to the extremely low incidence, to this date studies on the topic are limited to case reports and a few case series. This narrative review aims to resume literature on BPOP and provide an overview of its natural history, morphologic characteristics and prognostic horizon.

Materials and methods

A systematic research of the literature was done to identify studies reporting on patients who suffered from BPOP between 1983 and 2021. We collected data regarding aetiologic and pathogenetic theories, patients' personal data and anamnesis, lesions' location, clinical presentation, imaging features, pathological appearance, treatment and prognosis.

Results

We identified 322 cases of BPOP with a mean age of 34.3 years at the moment of diagnosis. There was no gender difference. The most involved site was the hand, followed by the foot. A history of trauma was reported for 14.7% of the cases. 38.7% of the patients had pain. Literature defined typical radiographic and microscopic patterns that characterize Nora lesions. While imaging is fundamental to orientate towards BPOP, histological evaluation is mandatory to get the definitive diagnosis. To this date, only reliable therapeutic option is represented by surgical resection. BPOP is burdened by a risk of recurrence that accounts to 37.4%.

Conclusion

BPOP is a rare benign disease that should be considered during the differential diagnosis of parosteal lesions, especially in the acral regions. Careful diagnostic evaluations are necessary to get the correct diagnosis and wide margins of resection are recommended to minimize the relatively high risk of local recurrence.

Bizarre Parosteal Osteochondromatous Proliferation (Nora Lesion) in Pediatric Phalanges

Bizarre parosteal osteochondromatous proliferation, or Nora tumor, is an uncommon lesion affecting the tubular bones of the hands and feet. Normally arising from the cortical surface and periosteum of these bones, these lesions histologically consist of a hypercellular cartilaginous cap covering a bony stalk that is surrounded by ossified areas and spindle cell stroma. The differential diagnosis includes conditions involving the periosteum such as chondrosarcoma, parosteal osteosarcoma, osteochondroma, turret exostosis, and florid reactive periostitis. The only effective treatment is wide surgical excision; nevertheless, local recurrence rates are extremely high and may necessitate revision surgery. In the present study, we report 3 cases of Nora lesion located in the hand in pediatric patients. The diagnosis in these cases was challenging owing to their presenting symptoms and radiographic findings. The diagnosis was made based on characteristic findings noted on the radiographic images and was confirmed by histological examination following excision.

Bizarre parosteal osteochondromatous proliferation: Rare case affecting distal ulna and review of literature

Bizarre parosteal osteochondromatous proliferation (BPOP) or Nora's lesion, is a rare benign surface-based bone lesion most commonly involving the tubular bones of hands and feet. We report an unusual case of BPOP affecting the distal ulna in a 22-year-old man who presented with a painless wrist mass following injury and was successfully treated with surgical resection. We focus on multi-modality imaging, histopathology, and differential diagnosis (including osteochondroma, florid reactive periostitis, myositis ossificans, and surface-type osteosarcoma), as well as a review of the literature regarding recent concepts on etiology and evolution, spectrum of imaging characteristics and diagnostic overlap, histopathology, as well as treatment options.

Bizarre Parosteal Osteochondromatous Proliferation (Nora's Disease)

Finger pain is a common presenting symptom. While some of the causes are rare and easily forgotten, they may be significant. Bizarre parosteal osteochondromatous proliferation is a rare benign tumour. Malignant transformation has been described. The distinctive radiological features and its differential diagnoses are discussed.

A Case Report of Heel Pain Mimicking Plantar Fasciitis and Osteosarcoma: A Unique Presentation of a Nora's Lesion

Bizarre parosteal osteochondromatous proliferation, otherwise known as "Nora's lesion," is a rare benign neoplasm first described by Nora in 1983. The exact etiology of this neoplasm remains unknown, and its presentation in the lower extremity presents a diagnostic challenge, as both clinical and radiologic features cannot fully differentiate it from other neoplasms. We present the case of a 48-year-old female with plantar heel pain secondary to Nora's lesion mimicking plantar fasciitis and periosteal osteosarcoma. Following bone biopsy for histopathologic analysis, the patient's symptoms spontaneously resolved, and she returned to activity with complete resolution of symptoms 18 months post biopsy. Bizarre parosteal osteochondromatous proliferation as an etiology for plantar heel pain has not been previously described in the literature. Although rare, it should be considered in the differential diagnosis for patients presenting with plantar heel pain, especially after failed conservative treatment. Following diagnostic confirmation by histopathology, complete surgical excision is the treatment of choice.

Bizarre parosteal osteochondromatous proliferation: a novel case report of recurrence in the toe

Bizarre parosteal osteochondromatous proliferation (BPOP) is an uncommon reactive mesenchymal lesion mainly affecting the small bones of the hands and feet. They frequently occur in young adults. It is important to understand and differentiate BPOP from other lesions, especially because of its atypical microscopic features and tendency to recur. We present a case of a recurrent lesion involving the toe and discuss management options. To our knowledge, our current case report is the first in the literature to report a recurring BPOP lesion of the toe.

A bizarre parosteal osteochondromatous proliferation (Nora's lesion) of metatarsus, a histopathological and etiological puzzlement

Nora's lesion (bizarre parosteal osteochondromatous proliferation) is a rare, benign lesion that is composed of differing amounts of cartilage, bone, and spindle cells and an unusual form of calcified cartilage so-called "blue bone". Whether it represents a reactive proliferation or a neoplastic lesion still remains controversial. We present a 24-year-old woman having a 4.5cm two lobulated mass attached to second metatarsus of her left foot. The lesion was hyperintense on magnetic resonance imaging and accompanied by an extensive soft tissue and bone marrow edema. In resection specimen, smaller lobule appeared stuck-on the cortex while the larger one had a broader base and a 0.4cm cartilaginous cap-like formation. The histological picture was best fit to Nora's lesion however showed less fibroblastic tissue and cartilaginous pleomorphism. The lesion also showed areas with cortical invasion and a small focus of fracture callus accompanied by adjacent medullary edema and fat necrosis. The case is presented with the comparative radiologic, macroscopic and microscopic findings for its diagnostic difficulties and etiopathogenetic considerations in favour of a maturation phenomenon in parosteal ostecartilaginous lesions irrespective of the cause.

Recurrent bizarre parosteal osteochondromatous proliferation of the ulna with erosion of the adjacent radius: case report

Bizarre parosteal osteochondromatous proliferation is an unusual entity that should be considered when evaluating a patient with a surface-based bone lesion. The aggressive features of bizarre parosteal osteochondromatous proliferation have occasionally led to misdiagnoses as malignant neoplasms and subsequent aggressive treatment. We present a case of a recurrent forearm bizarre parosteal osteochondromatous proliferation with unique radiographic features. This report serves to illustrate the importance of both radiographic and histopathologic review for correct diagnosis and discusses the successful management of a recurrent forearm lesion.

Bizarre parosteal osteochondromatous proliferation (Nora's Lesion) of the mandible. a rare bony lesion

Bizarre parosteal osteochondromatous proliferation (BPOP) also eponymically called "Nora's lesion", is a rare benign reactive bone lesion first reported in 1983. BPOP occurs classically on the bones of the hands and feet and long bones. This lesion can easily be confused, both clinically and microscopically, with other benign and malignant lesions of bone, including osteochondroma, parosteal osteosarcoma, myositis ossificans and reactive periostitis. BPOP has been reported to have a high rate of recurrence. Only 3 cases of BPOP of the head and neck have been reported in the literature, of which one involved the maxilla. We present a rare case of BPOP involving the mandible in a 10 year old African American male. Microscopically, a fibro-cartilaginous cap giving rise to a proliferation of variably mineralized osteophytic finger-like projections of bone was seen. Multiple trabeculae of "blue bone" were noted as well as numerous atypical appearing chondrocytes. The lesion recurred within 4 months following the initial excision but has not recurred to date after the second local excision. To the best of our knowledge, this is the first report of BPOP arising in the mandible. In addition, we discuss the clinical and microscopic features, differential diagnosis, and prognosis of this rare entity. We present a case of BPOP of the mandible and believe this is the first report of such a case in the mandible.

Bizarre parosteal osteochondromatous proliferation of bone: clinical management of a series of 22 cases

We describe 22 cases of bizarre parosteal osteochondromatous proliferation, or Nora's lesion. These are surface-based osteocartilaginous lesions typically affecting the hands and feet. All patients were identified from the records of a regional bone tumour unit and were treated between 1985 and 2009. Nine lesions involved the metacarpals, seven the metatarsals, one originated from a sesamoid bone of the foot and five from long bones (radius, ulna, tibia, and femur in two). The mean age of the patients was 31.8 years (6 to 66), with 14 men and eight women. Diagnosis was based on the radiological and histological features. The initial surgical treatment was excision in 21 cases and amputation of a toe in one. The mean follow-up was for 32 months (12 to 162). Recurrence occurred in six patients (27.3%), with a mean time to recurrence of 49 months (10 to 120). Two of the eight patients with complete resection margins developed a recurrence (25.0%), compared with four of 14 with a marginal or incomplete resection (28.6%). Given the potential surgical morbidity inherent in resection, our data suggest that there may be a role for a relatively tissue-conserving approach to the excision of these lesions.

Unusual presentation of bizarre parosteal osteochondromatous lesion of the second toe (Nora's lesion)

Bizarre parosteal osteochondromatous proliferation (BPOP) of bone is a rare benign neoplasm. This report presents the first case of BPOP associated with gangrenous changes and ulceration after remaining symptomless for 20 years. The authors hypothesize that the cause of gangrene may be attributed either to vascular occlusion due to pressure, trauma, or malignant transformation of the lesion. Although local excision of the tumor is the treatment of choice, the authors resorted to ray excision, as gangrenous changes and ulceration were present and there was the possibility of malignant change.

Tumours of the hand: a review on histology of bone malignancies

Malignant bone tumours of the hands are uncommon. Although almost all lesions that occur in other parts of the skeleton can also affect the hands, their frequency, distribution and clinical characteristics differ. This review focusses on the histology of these tumours and gives an overview of the main differential diagnoses. Close correlation to radiologic and clinical features usually leads to the correct diagnosis.

Benign parosteal osteochondromatous proliferation of the hand originally diagnosed as osteochondroma: a report of two cases and review

Bizarre parosteal osteochondromatous proliferation (BPOP) is a rare cartilaginous neoplasm that often presents in the long bones of the hands and feet. BPOP is a benign but locally aggressive fibro-osseous mass that has striking clinical, radiographic, and histologic similarities with osteochondroma. Differentiating between the two lesions is important as BPOP often requires more extensive surgical resection and has a higher recurrence rate compared to osteochondroma. This report presents two cases of BPOP where initial clinical diagnosis of osteochondroma was made even after appropriate imaging and histologic samples were evaluated. This report reviews clinical, radiographic, and histologic characteristics that can differentiate between the two lesions.

Bizarre parosteal osteochondromatous proliferation of the metatarsal: a pediatric case report and archival review

Bizarre parosteal osteochondromatous proliferations (BPOP), also known as Nora's lesions, are rare tumors occurring most commonly in the hands and feet. They are benign and rarely exhibit radiological evidence of cortical invasion. We report a case of BPOP showing atypical magnetic resonance imaging features that are inconsistent with BPOP and having a novel chromosomal aberration. We also review the BPOP cases in our regional benign bone tumor database.

LEVEL OF CLINICAL EVIDENCE

4.

La lésion de Nora ou Bizarre Parosteal Osteochondromatous Proliferation

The lesion Nora described in 1983 as a bizarre parosteal osteochondromatous proliferation (BPOP) is a member of a group of osteocartilaginous surface lesions. BPOP is infrequent but new cases are regularly reported. We report two new cases with an unusual localization (ilion and distal humerus) and unusual size (9 cm for the iliac lesion). In light of these cases and reports in the literature, the main differential diagnoses of BPOP are exostosis and parosteal osteosarcoma.

Bizarre parosteal osteochondromatous proliferation of the proximal humerus: case report

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora's lesion, is a rare lesion of bone occurring predominantly in the long bones of the hands and feet. It exists as a puzzling clinical entity of uncertain origins and high recurrence rates after surgical resection. To our knowledge, this clinical entity has not been reported in the proximal aspect of the humerus. An interesting report of a lesion occurring in the proximal humerus, which initially was misinterpreted as a parosteal osteosarcoma, is discussed outlining the clinical, radiographic and pathologic features of the BPOP lesion.

Prolifération ostéocartilagineuse parostéale bizarre ou tumeur de Nora. À propos de deux cas

Bizarre parosteal osteochondromatous proliferation, or Nora's tumor, is an uncommon lesion, involving mostly tubular bones of hands and feet, arising from the cortical surface. It must be distinguishable from chondrosarcoma, parosteal osteosarcoma and florid reactive periostitis. It is a benign lesion, characterized by a proliferation of chondroid, bony and fibrous tissues. The authors report two cases involving the hand. The diagnosis can be made thanks to imaging techniques and confirmed by histological examination. The treatment is surgical, namely complete excision but there is a high rate of local relapse.

Bizarre parosteal osteochondromatous proliferation (Nora's lesion) in the hand

PURPOSE

The purpose of this study was to review our experience with a benign surface bone lesion referred to as bizarre parosteal osteochondromatous proliferation (BPOP) or Nora's lesion, named for the pathologist who described it in 1983. The lesion may be confused with a variety of tumors, particularly solitary osteochondromas, which are rare.

METHODS

The files in the Department of Pathology at the Hospital for Joint Diseases were reviewed over a 21-year period for all surface bone lesions involving the tubular bones in the hand. There were a total of 10 cases of BPOP compared with only a single case of an osteochondroma.

RESULTS

Radiographs generally showed a well-marginated uniformly dense mass arising from the surface of the affected bone without any disruption in its bony architecture. Surgical excision is the definitive treatment and included the fibrous pseudocapsule over the lesion, any periosteal tissue beneath the lesion, and any area of the cortex of the host bone that appeared abnormal. Although in the medical literature the recurrence rate for BPOP is high, we had only one recurrence in our series.

CONCLUSIONS

BPOP is a benign surface bone lesion that may be confused with benign and malignant tumors. Although there is a cleavage plane between the lesion and host bone, we recommend excising the pseudocapsule over the lesion, any periosteal tissue beneath the lesion, and decorticating any abnormal-appearing areas in the underlying host bone. This may explain the low recurrence rate in our series.

Bizarre parosteal osteochondromatous proliferation (Nora's lesion): a retrospective study of 12 cases, 2 arising in long bones

Twelve cases of bizarre parosteal osteochondromatous proliferation (BPOP), also known as Nora's lesion, are reported. Ten lesions were located in the small bones of the hands, and 2 were located in long bones (femur and proximal tibia). Patient age ranged from 12 to 63 years (average, 30.3 years). Radiography of the lesions in the hand bones showed calcific masses attached to the underlying cortex, without interruption of the latter. The long bone lesions revealed unusual findings. In the femur, BPOP presented with extensive cortical destruction and was suggestive of a malignant lesion. This presentation has not been described to date. In the tibia, the lesion was located in the soft tissue without cortical attachment. This type of BPOP probably represents an immature lesion that over time will mature to solid cortical attachment. On histologic examination, all lesions demonstrated 3 distinct components with variable degrees of representation: (1) hypercellular cartilage with calcification and ossification, with the calcified cartilage having a characteristic basophilic tinctorial quality; (2) cancellous bone undergoing maturation; and (3) spindle cell stroma without cytologic atypia. In 1 case with a long-standing history, the cartilaginous component was minimal. BPOP, together with florid reactive periostitis and turret exostosis, may represent different stages in the development of a posttraumatic proliferative process. BPOP apparently arises from the periosteal tissues through a process of cartilaginous metaplasia.