Bilateral hand X-rays were performed in a 58-year-old man for suspicion of arthritis.
An incidental osseous lesion was found in the left wrist (Fig. 1). Radiographs showed an eccentric expansile epimetaphyseal bone lesion in the distal radius that abutted the articular surface. There was no evidence of cortical destruction. The lesion had a predominantly ground-glass appearance with some remnant trabeculae and internal foci of sclerosis. It had a well-defined wedge-shaped lytic leading margin without marginal sclerosis. Radiocarpal joint space was preserved.
MRI was performed (Fig. 2) showing a lesion with heterogeneous signal intensity: increased signal intensity on PD and T2W images and low signal intensity on T1W images with foci of intermixed yellow marrow.
The lesion was misdiagnosed as a giant cell tumour and the patient underwent surgery. Anatomopathological study demonstrated typical findings for Paget disease, which are shown on Figure 3. Multiple multinucleated osteoclastic giant cells and osteoblasts were seen, causing both osseous resorption and formation.
The disease was named after Sir James Paget, who first described it as “osteitis deformans” in 1877 [1]. It is a common disease that usually occurs in people over 40 years of age [2].
Twenty percent of patients are asymptomatic at diagnosis [3].
Three sequential stages, that may coexist, have been described for Paget disease. Stage I is the osteolytic phase in which osteoclasts are activated causing bone resorption. Stage II is the mixed lytic and blastic (active) phase and corresponds to an osteoblastic activation with osseous formation in response to osteoclastic bone resorption. Stage III is the blastic phase in which osteoblastic activity decreases [4].
Anatomopathologically, this results in thickened and disorganized trabeculae, forming a mosaic pattern, with characteristic basophilic cement lines along the thickened trabeculae. The normal yellow marrow is replaced by fibrovascular tissue in the active phase [3].
The axial skeleton is the most commonly affected, the most frequent locations being the pelvis, spine and skull [3].
The osteolytic phase predominates in the long bones [2]. The radiographic appearance is that of a bone lesion with a well-defined, wedge-shaped osteolytic leading margin, without marginal sclerosis, that represents the osteolytic phase. This leading margin is similar to a flame or a blade of grass, a feature that is unusual for a neoplasia. The osteolytic phase almost always begins in the subchondral bone of the epiphysis and advances (about 1 cm per year) into the metaphysis and diaphysis. Behind the lytic leading margin, mixed lytic and blastic phase disease develops with a disorganized pattern. Cortical bone thickening and trabecular bone thickening with bone expansion characteristically develop. In other cases, like ours, a hazy ground-glass or “washed-out” pattern might be seen with obliteration of bony trabeculae [2]. Internal focal zones of sclerosis can be observed in the epiphysis or metaphysis while the lytic phase extends towards the diaphysis.
MRI appearance depends on the stage and consequent histological composition of the lesion [3]. In the lytic to early active phase the lesion has heterogeneous signal intensity with typically intermixed foci of maintained yellow (fatty) marrow, that exclude malignant transformation.
As in our case, Paget disease might be discovered incidentally in asymptomatic patients. Therefore, it is important to be familiar with its typical radiographic appearance to avoid misdiagnosis. Radiologists should consider it in the differential diagnosis of epiphyseal or epimetaphyseal bone lesions with a well-defined osteolytic margin.
Paget disease of the distal radius
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Based on the provided bilateral hand X-rays, pathological slides, and MRI images, the following key features can be observed:
• On the X-ray of the hands, near the distal radius (or close to the articular surface), there is a well-defined focal area of abnormal radiolucency appearing wedge-shaped or “flame-like.” Local cortical thickening is visible, and in some areas, a “ground-glass” density is evident.
• The images indicate that the lesion is located in the cancellous portion of the bone (mostly from the epiphysis to the metaphysis). Compared to typical destructive changes (such as tumor infiltration), its edges are sharper, with no obvious periosteal reaction or significant soft tissue mass.
• MRI findings suggest uneven signal changes in the cancellous bone near the joint. Some areas still retain fatty signals, indicating normal or partially normal yellow marrow. Enhancement suggests the possible replacement of bone marrow by fibrous vascular tissue.
• The histopathological slides (HE staining) reveal thickened, irregular bony trabeculae arranged in a dense or mosaic pattern. Some regions show distinct blue-stained cement lines (baseline) along with fibrous vascular tissue replacing the normal marrow spaces.
Considering the patient’s age (58 years), the incidental finding of the lesion (absence of significant symptoms), as well as the radiological and pathological features, the main possible diagnoses and their considerations include:
• Paget’s Disease (Osteitis Deformans):
- Commonly seen in individuals over 40 years old. Radiologically, it often presents as both lytic and sclerotic changes in the bone, with the characteristic “flame-shaped” or “blade of grass” lesion margin, disorganized and thickened trabeculae. Microscopically, the classic mosaic pattern of bone and fibrous vascular tissue replacing the marrow are seen.
• Giant Cell Tumor of Bone (GCT):
- Often occurs around the metaphyseal-epiphyseal region of long bones. X-rays show a well-defined lytic lesion. However, its pattern of bone destruction is usually more aggressive and often extends to the articular surface. Clinically, there is often pain or other symptoms. Pathologically, numerous multinucleated giant cells are characteristic.
• Subacute Osteomyelitis or Other Chronic Inflammatory Conditions:
- May present as focal lytic lesions or sclerotic areas, but typically accompanied by local redness, swelling, or signs of inflammation. MRI usually shows marked bone marrow edema signal, which does not fully match this asymptomatic case.
• Other Benign Bone Lesions (e.g., Bone Cyst, Osteochondroma, etc.):
- Often exhibit more typical morphological features (e.g., the cartilaginous cap of osteochondroma, fluid density of a bone cyst), which do not entirely correspond to the “flame-shaped” margins and mosaic bone structure seen pathologically in this case.
Taking into account the patient’s age, clinical presentation (no obvious pain or symptoms), the characteristic changes in the bones shown in both hands on X-ray and MRI, and the pathological findings of mosaic-like remodeled trabeculae and fibrous vascular components, there is strong support for a diagnosis of
Paget’s Disease (Osteitis Deformans).
For further clarification if required, serum alkaline phosphatase (ALP) testing and whole-body bone scintigraphy can be used to assess the extent of the disease. If severe pain, deformity, or suspicion of malignant transformation appears clinically, percutaneous biopsy or more comprehensive imaging examinations may be considered.
(1) Treatment Approach
• For asymptomatic or minimally symptomatic patients: regular follow-up is advised, along with monitoring of serum alkaline phosphatase and other indicators. If there is no significant risk of pathological fracture, active intervention may not be necessary.
• Pharmacotherapy:
- Bisphosphonates (e.g., Alendronate, Zoledronic Acid) are first-line treatments for Paget’s disease, effectively inhibiting osteoclast activity and slowing disease progression.
- Calcium and Vitamin D supplementation may help maintain balanced bone metabolism.
• Surgical Intervention: primarily for cases with bone deformities, severe joint damage, or fractures. Options include corrective osteotomy or internal fixation.
(2) Rehabilitation and Exercise Prescription
• Goal: Maintain appropriate load on the bone to slow down destructive changes, improve muscle strength and joint function, and reduce the risk of fractures.
• Basic Principles (FITT-VP):
- Frequency: Perform low-impact weight-bearing exercises (e.g., walking, elliptical trainer, or stationary cycling) 2 to 3 times a week.
- Intensity: Begin with low to moderate intensity (subjective effort around 5–6 out of 10) and gradually increase based on tolerance.
- Time: Exercise for 20–30 minutes each session, possibly in segments to avoid excessive fatigue.
- Type: Low-impact aerobic activities combined with moderate resistance exercises (e.g., resistance bands or light dumbbells), ensuring joint stability.
- Progression: Increase frequency, resistance, or duration gradually, according to individual tolerance and bone/joint condition, ensuring safety.
- Volume & Individualization: Adjust exercise regimens based on the fragility of the affected bones, follow medical advice, and tailor progression to personal tolerance. If necessary, perform under the supervision of a rehabilitation therapist.
• Special Note: If there is noticeable bone change, high-impact exercise (such as excessive running or jumping) should be avoided to reduce the fracture risk; patients with underlying cardiovascular or other comorbid conditions should undergo an assessment of cardiac and pulmonary function before formulating an exercise plan.
Disclaimer: This report is a reference medical analysis based on current imaging and pathological information and does not substitute for an in-person consultation or a professional physician’s medical advice. Patients should make final treatment and rehabilitation decisions in conjunction with their actual condition and professional healthcare guidance.
Paget disease of the distal radius
