A 16-year-old male patient presented with a 1-year history of progressive right wrist pain.
He visited other medical centres where he was treated for de Quervain's tenosynovitis.
The pain was located in the distal scaphoid pole, more intense at night and not related to trauma or manual activities.
Posteroanterior X-ray of right wrist shows an osteolytic lesion of trapezium (Fig. 1).
Magnetic resonance imaging (MRI) confirmed the presence of signal changes at scapho-trapezium (ST) articulation, soft tissue mass and inflammatory changes extending into the extensor tendons compartment. The differential diagnosis was made between benign and malignant tumour and inflammatory lesion. (Fig. 2 and Fig. 3).
A CT was also performed and confirmed the osteolytic lesion at scapho-trapezium articulation. (Fig 4, Fig. 5 and Fig. 6).
The Dual-Phased bone Gammagraphy study detected a moderate hypervascularization with osteoblastic increased activity on the right hand (Fig. 7).
Histological analysis of the trapezium showed connective tissue containing osteoid and primitive bone rimmed by osteoblasts next to numerous giant cells. There was no area suspicious for malignancy (Fig. 8).
The treatment was tumour curettage with allogenic bone grafting. (Fig. 9).
At 12-month follow–up evaluation, no recurrence was observed (Fig. 10).
The patient remains asymptomatic without limitations in his activities.
Osteoblastoma represents 1% of all primary bone tumours [3] and is a rare pathology in the carpus, and has never been described in the trapezium to the best of our knowledge.
It affects men more than women with an incidence of 2-3:1, and more frequently patients younger than 30 years [2].
It is often seen in long bones, but it has a predilection for vertebral bodies.
Osteoblastoma is locally aggressive and resembles osteoid osteoma but it is larger in size (> 2 cm) and in contrast, pain is inconsistently relieved with salicylates [7, 4]. The pain is not intense and poorly localized, which can lead to a delayed diagnosis [1, 6]. Osteoid osteoma shows indeed the characteristic radiolucent nidus.
There are also differences in the natural history of both tumours: Osteoid osteoma tends to regress, while osteoblastoma is progressive and may undergo malignant transformation, although this still remains a controversy [8].
X-ray and CT are the "gold standard" for the diagnosis; CT examinations are best used to further characterize the lesion with regard to the presence of a nidus and matrix mineralization. However, when it presents with an aggressive pattern and soft tissue mass, MR is mandatory. Typical osteoblastoma has decreased signal intensity on T1 and variable on T2-weighted images. Due to calcified matrix, osteoblastoma can manifest as heterogeneously hypointense relative to marrow on non-fat-suppressed T2-weighted images [2].
Despite the fact that osteoblastomas accumulate radionuclide on bone scintigraphy studies, it is not specific [2].
For the differential diagnosis a percutaneous excisional CT-guided biopsy is appropriate. The histological characteristics between osteoid osteoma and osteoblastoma may be challenging. Both are osteoid formers but in the latter bone trabeculae are wider, longer and less cohesive [8].
Osteoblastoma easily recurs after incomplete surgical removal (around 20% of recurrence rate). Curettage and grafting are the treatments of choice and for recurrence en bloc resection with arthrodesis [3, 5]. A close monitoring of these patients is mandatory [2].
Osteoblastoma is an uncommon benign tumour, rarely found in the hand. So it should be recognized as a still possible cause of long term wrist pain.
For the diagnosis, plain films and CT examinations are the "gold standard", but for the more aggressive type, MR can be a useful tool.
Osteoblastoma
Based on the patient’s previous imaging studies (including X-ray, CT, MRI, and bone scan), the following major features are observed:
1. The lesion is located in the proximal-distal region of the right wrist, primarily involving the distal pole of the scaphoid or the trapezium, showing localized bone changes.
2. Plain X-ray and CT scans indicate a mixed-density pattern, with areas of sclerosis and radiolucency. Suspicious “bone trabecula” proliferation can be suggestive of a benign osteogenic lesion.
3. MRI shows that the lesion appears hypointense on T1-weighted sequences and may present heterogeneous signal changes on T2-weighted sequences. No significant diffuse edema is found in the adjacent soft tissue, but there is mild involvement of the peripheral soft tissue at the margin.
4. The bone scan reveals a localized hotspot, indicating increased bone activity. However, this is not highly specific; pathological evidence or further imaging evaluation is needed for clarification.
5. Histopathology (from CT-guided biopsy or surgical specimens) shows an increased number of osteoblasts and bone matrix formation, with wide and irregularly arranged bone trabeculae.
Taking into account the patient’s clinical presentation (worsening nocturnal pain, relatively young age, gradual progression without obvious trauma history), imaging findings (X-ray, CT, MRI showing a local osteogenic lesion greater than 2 cm in diameter, with pain not readily relieved by simple analgesics), and histopathology (active osteoblasts and newly formed bone trabeculae), the most likely diagnosis is: Osteoblastoma of the Carpal Bone.
1. Surgical Treatment
• The first choice is curettage of the lesion and bone grafting to reduce the recurrence rate.
• In cases of local recurrence or larger lesions with extensive involvement of surrounding tissues, en bloc resection may be considered, with partial arthrodesis if necessary.
2. Postoperative Rehabilitation and Exercise Prescription
• Early Postoperative Phase (Weeks 1–4): Focus on wound healing and preventing excessive wrist motion. Under protection with a cast or brace, perform finger exercises and isometric contractions of the forearm muscles to maintain muscle strength.
• Intermediate Rehabilitation (Weeks 4–8): After removing the cast or brace, gradually begin passive and active range-of-motion exercises (such as gentle fist making, wrist flexion-extension, and forearm pronation-supination). Perform low-intensity grip exercises within the tolerable pain range.
• Late Rehabilitation (Weeks 8–12): Strengthen the wrist and forearm muscles with resistance exercises (e.g., using elastic bands or light dumbbells, progressively increasing the load) and include coordination and proprioception training (e.g., grip trainers, finger dexterity exercises). Focus on restoring joint range of motion and avoid high-impact or high-intensity activities.
• Exercise Modality and Progression (FITT-VP Principle):
– Frequency: 3–5 times per week. In the early stage, brief joint ROM exercises can be done daily.
– Intensity: Start with low intensity, guided by pain tolerance, and gradually increase resistance or load.
– Time: 15–30 minutes per session, gradually lengthening as tolerance and function improve.
– Type: Emphasize range-of-motion training, light resistance training, and muscle coordination and balance exercises. Later stages can include more functional drills (e.g., light racket or ball gripping).
– Progression: Adjust the program according to joint pain and swelling; avoid overexertion and progress gradually.
3. Follow-Up
• Osteoblastoma has a certain recurrence rate (up to 20%), requiring regular clinic or imaging follow-up to monitor local bone healing and potential recurrence.
• If persistent pain, joint stiffness, or worsening functional impairment occurs, prompt re-evaluation is advised.
This report is a reference analysis based on current clinical and imaging data. It does not replace an in-person consultation or professional medical advice. If further questions arise or the patient’s condition changes, prompt assessment by an orthopedic specialist and adherence to medical advice are recommended.
Osteoblastoma
