59 year old male presented with six week history of pain in the right wrist and difficulty in carrying out his work, as a caster in the potteries.
Radiographs of the hand and wrist revealed proliferative bony outgrowths arising from anterior aspect of radial styloid and the base and head of first metacarpal. Several ossicles were seen on radial and palmar aspect of the carpus. In addition, there were degenerative changes at the first carpo-metacarpal joint. Differential diagnosis included BPOP and reactive osteochondroma ( Turret exostosis)
BPOP or Nora’s lesion was described by Nora et al in 1983(1). It is a rare, benign lesion commonly affecting the hands and feet, predominantly proximal phalanges, middle phalanges, metacarpals and metatarsals. Additional sites of involvement include long bones, skull and maxilla. To date, there are no cases in the literature describing the involvement of the carpals, as is seen in our case. Males and females are equally affected and cases have been reported from eleven years (2) to old age (4). Although history of trauma is evident in some affected patients (5, 6), it is not constant and the aetiology of the lesion is not clear (3). BPOP typically presents as a painless or painful mass that grows over a period of weeks to months. Histologically, they are composed of hypercellular, highly calcified cartilage showing disorganized endochondral ossification (3, 4). On plain radiographs, BPOP appears as a well defined bony mass which characteristically does not show continuity of medullary canal of the underlying bone with the lesion (3, 4, 6). Differential diagnoses include osteochondroma, ossifying haematoma or myositis ossificans, florid periostitis and soft tissue chondroma (4). Some authors feel that florid reactive periostitis, BPOP and Turret exostosis represent different phases of a reactive process occurring at the bone surface (8). These have also been referred to as proliferative periosteal processes (9). CT helps to distinguish BPOP from ostechondroma by showing the absence of continuity of the medullary canal and lack of the characteristic orientation of an osteochondroma which is away from the physis. In contrast to malignant lesions, BPOP exhibits no periosteal reaction. The underlying bone and soft tissues appear normal radiologically (7). The histology may look aggressive with architectural and cytologic atypia if assessed without the clinico radiological findings (8) On MRI, these lesions appear as low signal on T1, variable signal on FSE T2 & Gradient echo and high signal on STIR. The absence of soft tissue swelling, cortical destruction, as well as lack of stress fracture or medullary involvement are all useful features to define their true nature (10). The cortical bone is intact and there is homogenous intramedullary enhancement with gadolinium (11) BPOP is known to recur locally in 50% of cases after resection (4) Removal of the lesion intact with excision of the pseudocapsule as well as any periosteal tissue beneath the lesion and decorticating any abnormal areas of host bone results in a lower recurrence rate (12) . Metastatic lesions have not been reported.
Bizzare parosteal osteochondromatous proliferation (BPOP)
The patient is a 59-year-old male. X-ray imaging of the right wrist shows a focal, lobulated bony density near the distal radius and around the carpal bones, with relatively clear boundaries. The protruding part is contiguous with the cortex but lacks obvious continuity with the medullary cavity. Calcification is visible within the lesion, and there is no apparent cortical destruction or reactive periosteal thickening. No significant soft tissue swelling or abnormal calcification is observed.
These diagnoses mainly consider the morphological features of the lesion (continuity or lack thereof with the medullary cavity, distribution of cartilage and osseous components), combined with the patient’s symptoms, disease course, and imaging findings.
Taking into account the patient’s age, symptoms (6 weeks of local persistent pain and functional impairment), occupational characteristics (repetitive hand operations), imaging findings (a lesion around the carpal bones, connected to the cortical surface without medullary continuity, and no obvious abnormalities in the surrounding soft tissue), and references to pathological findings (the lesion’s cartilaginous and irregular osseous proliferation may be mistaken for malignancy, though it is often a benign overgrowth), the most likely diagnosis is:
Bizarre Parosteal Osteochondromatous Proliferation (BPOP, Nora’s lesion).
Further confirmation could be obtained through surgical biopsy and pathological analysis (including cartilage components and irregular endochondral ossification) to exclude other benign or malignant bone tumors.
1. Treatment Strategies:
2. Rehabilitation / Exercise Prescription Recommendations:
(FITT-VP principle: Frequency, Intensity, Time, Type, Volume, Progression, for continuous adjustment.)
Safety Considerations: For patients with low bone density or compromised cardiopulmonary function, slow progression of rehabilitation is advised to avoid excessive loading or extended immobilization that may lead to secondary injury.
Disclaimer:
This report is based on the existing medical history and imaging data for reference only and does not replace in-person consultation or professional medical advice. If any questions arise or symptoms worsen, please seek immediate medical attention for further evaluation.
Bizzare parosteal osteochondromatous proliferation (BPOP)
