Bizarre parosteal osteochondromatous proliferation: 16 Cases with a focus on histologic variability

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 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.

Bizarre parosteal osteochondromatous proliferation Nora's lesion: Case report of two cases with review of the literature

ABSTRACT

Bizarre parosteal osteochondromatous proliferation (BPOP) is also known as Nora's disease. It is a benign lesion. Even though recent studies showed probable neoplastic etiology, the exact cause is unknown. BPOP commonly involves small bones of hands and feet. This condition is rare and very few cases are reported. In this report, two cases are presented with clinical, radiological, and histopathological findings. The first case was a 38-year-old female presented with 3-year history of mild painful swelling in the left middle finger and the second case was a 28-year-old male with the left leg swelling for 8 years. On radiology, both cases showed surface lesion with uninvolved medullary cavity. Excision specimen of both the lesions subjected for histopathological examination. Microscopically, there was irregular maturation of the bone and cartilage. Cartilage showed purplish-blue color (blue bone) with bizarre chondrocytes. BPOP is a rare benign condition. Awareness of clinical radiological and microscopic findings is needed for correct diagnosis and to differentiate it from other mimicking benign and malignant conditions.

Bizarre parosteal osteochondromatous proliferation: an educational review

Bizarre parosteal osteochondromatous proliferation (BPOP) is a surface-based bone lesion belonging to the group of benign chondrogenic tumors. The aim of this review is to familiarize the readers with imaging features and differential diagnosis of BPOP, also addressing pathological presentation and treatment options. The peak of incidence of BPOP is in the third and fourth decades of life, although it can occur at any age. Hands are the most common location of BPOP (55%), followed by feet (15%) and long bones (25%). On imaging, BPOP appears as a well-marginated mass of heterotopic mineralization arising from the periosteal aspect of the bone. Typical features of BPOP are contiguity with the underlying bone and lack of cortico-medullary continuity, although cortical interruption and medullary involvement have been rarely reported. Histologically, BPOP is a benign bone surface lesion characterized by osteocartilaginous proliferation with disorganized admixture of cartilage with bizarre features, bone and spindle cells. Differential diagnosis includes both benign-such as florid reactive periostitis, osteochondroma, subungual exostosis, periosteal chondroma and myositis ossificans-and malignant lesions-such as periosteal chondrosarcoma and surface-based osteosarcoma. Treatment consists of surgical resection. Local recurrences are common and treated with re-excision.Critical relevance statement Bizarre parosteal osteochondromatous proliferation is a benign mineralized mass arising from the periosteal aspect of bone cortex. Multi-modality imaging characteristics, pathology features and differential diagnosis are here highlighted to familiarize the readers with this entity and offer optimal patient care.

Misdiagnosis of Extraskeletal Osteochondroma in the Foot: A Report of 3 Cases

CASES

Two women presented with newly growing callosities beneath the first and second metatarsal heads, initially believed to reflect gastrocnemius tightness and plantar plate pathology. In another man, swelling at the posterolateral aspect of the heel was mistaken for a Haglund deformity. Subsequent imaging of each patient led to delayed diagnosis of extraskeletal osteochondroma (ESO). Surgical excision resolved symptoms in all 3 with no recurrence over 12 months later.

CONCLUSIONS

Whenever bony prominences newly develop in soft tissues of the foot, ESO should be suspected and appropriate imaging obtained. We describe physical features to help differentiate ESO from other common causes of foot overload.

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.

Fibro-Osseous Pseudotumor

Fibro-osseous pseudotumor is an extremely rare subcutaneous benign ossifying lesion associated with bone formation that is most commonly seen in the hands, followed by the toes. Because the tumor has a certain degree of invasiveness, it is often mistaken for malignancy, which leads to radical, excessive treatment. Our case involved a 32-year-old man with lesions on the left index finger. We documented the detailed data of diagnosis, treatment, and follow-up. We also conducted a review and summarized the published cases to advance our understanding of the disease, provide more accurate diagnostic criteria, and avoid inappropriate surgical procedures. [Orthopedics. 2021;44(6):e713-e718.].

Some Reactive Lesions of Bone Are Probably Neoplasms: A Review

CONTEXT.—

A number of fibro-osseous and osteocartilaginous lesions, especially common in the small bones of hand and feet, pose a diagnostic challenge and have historically been thought to be reactive lesions. However, modern molecular techniques when supplementing clinical, radiographic, and histologic evaluation suggest they may, in fact, be neoplasms.

OBJECTIVE.—

To review the clinical presentation and histopathologic, molecular, and radiologic features of selective bone lesions, focusing most specifically on subungual exostosis, florid reactive periostitis, and bizarre periosteal osteochondromatous proliferation.

DATA SOURCES.—

Literature review and personal experience are the source of this review.

CONCLUSIONS.—

Some lesions previously thought to be reactive are locally aggressive and demonstrate reproducible molecular abnormalities, and thus may be neoplasms. Although most common in the bones of the fingers and toes, these lesions also occur in long and other bones. The clinical presentations, radiologic appearances, and histopathologic features often overlap, making the diagnosis challenging, and these lesions may require molecular evaluation to maximize accurate prognostication.

Cutaneous aneurysmal bone cyst-First report of a case and literature review

Aneurysmal bone cyst (ABC) is a benign, expansile, multiloculated and blood-filled cystic lesion most commonly involving bones. We report herein the case of a 78-year-old woman with a dermal ABC located in the skin of the right foot. Histologically, the lesion displayed characteristic features of ABC, including blood-filled cystic spaces lined by loose connective tissue, admixed with solid areas composed of spindle cells and osteoclast-like giant cells, associated with foci of woven bone formation and matrix calcification ("blue bone" formation). Fewer than 30 cases of extraosseous ABCs have been described in soft tissues and, to the best of our knowledge, ABC primarily occurring in the skin, not associated with an underlying lesion in the bone, has not so far been reported in the literature.