In case of intra-articular osteoid osteoma, misdiagnosis as juvenile arthritis may occur, delaying adequate treatment. We report cases of intra-articular osteoid osteomas in children that were misdiagnosed and initially inappropriately treated with intra-articular corticoid injection. Diagnosis of osteoid osteoma was finally given by CT-scan and appropriate treatment by radiofrequency ablation or surgical ablation was performed. Clinicians and radiologists should be aware of the potentially confusing clinical and imaging findings associated with intra-articular osteoid osteoma.
Osteoid osteoma (OO) is a small benign tumor observed in children and young adult patients described for the first time by Berstrand in 1950 and defined by Jaffe in 1953 [
The typical clinical manifestations are nocturnal pain, unrelated to physical activity, increased by rest, and relieved by aspirin. The tumor is composed of a nidus of vascular osteoid tissue and woven bone lined by osteoblasts. It is frequently associated with considerable surrounding inflammation. The diagnosis is usually straightforward when imaging reveals a radiolucent nidus surrounded by variable degrees of reactive sclerosis. However, the diagnosis can be elusive when osteoid osteoma occurs in atypical locations, as they may have a nonspecific and misleading appearance on different imaging modalities, particularly on MRI [
CT-guided percutaneous ablation is now widely performed (radiofrequency ablation or laser ablation).
We report cases of intra-articular OO initially diagnosed as juvenile arthritis in which misdiagnosis led to inappropriate treatment (Table
Clinical data of the patients.
Sex | Age (years) | Initial symptoms | Location | Initial imaging | Initial treatment | Delay before correct diagnosis from symptoms onset |
---|---|---|---|---|---|---|
F | 14 | Permanent hip pain, limping, improved with NSAIDs, and |
Femoral neck, intra-articular | (i) Radiograph: normal |
(i) Naproxen 250 mg 2 times a day |
6 months |
|
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F | 15 | Permanent hip pain, limping, |
Femoral neck, intra-articular | (i) Radiograph: normal |
(i) Diclofenac 3 times a day |
7 months |
|
||||||
M | 8 | Permanent ankle pain, limping, night worsening, |
Talar neck, intra-articular | (i) Radiograph: ankle joint swelling |
(i) Ibuprofen 3 times a day |
4 months |
|
||||||
F | 6 | Permanent hip pain, limping, and decreased ROM | Femoral neck, intra-articular | Radiograph: normal | (i) Naproxen 2 times a day |
6 months |
Because of pain persistence 6 weeks later, she consulted our clinic for a second opinion. She had a painful range of motion limitation of the right hip. Hip radiography, hip echography, and bone scan were performed (Figure
14-year-old girl with intra-articular osteoid osteoma of the right femoral neck. (a) Frontal X-ray of the pelvis, interpreted as normal. (b) Bone scan, demonstrating increased uptake of the right hip joint. (c) Hip ultrasound, longitudinal scan, showing synovial thickening of the anterior articular recess, right hip.
Same patient as in Figure
One month later, she was reviewed by the pediatric orthopedist with the same symptomatology. She was taking 4 g of paracetamol and 150 mg of diclofenac a day without improvement of symptoms. Clinical examination revealed decreased hip internal rotation and abduction. A bone scan was performed, showing right femoral neck hyperfixation. No argument was found in favor of an OO or osteomyelitis but a CT-scan was performed in the hyperfixation area. The CT-scan found a 6 mm nidus in the anterior edge of the femoral neck and surrounding hyperostosis. The diagnosis was made seven months after the onset of symptoms.
The patient underwent a radiofrequency ablation under general anesthesia. One-day hospitalization was necessary. The pain disappeared completely some day after the surgery. One month after surgery, the mobility of the hip was improved. Abduction and internal rotation became identical to the contralateral side. Only external rotation was less than the contralateral side (30°/45°). At the last followup the patient kept a slight decrease of the external rotation compared to the contralateral side. No recurrence of OO was observed after 2 years of followup.
8-year-old boy with osteoid osteoma of the left talar neck. Synovial thickening of the ankle and subtalar joint was diagnosed with echography. X-ray showed ankle effusion but no bone anomaly was initially reported. However retrospective X-ray analysis showed a talar neck hyperostosis.
Four days later the patient was seen in general pediatric clinic with relative pain improvement but with persistence of skin redness and ankle swelling. The blood biology and urinary sediments did not found any argument of inflammatory pathology.
He was seen 10 days later by pediatric rheumatologist without significant symptoms improvement. He also concluded to idiopathic juvenile arthritis. The patient underwent an intra-articular methylprednisolone acetate injection under general anesthesia and two weeks later additional methotrexate was given 10 mg a week with folic acid. No symptomatology improvement occurred.
Considering the persistence of symptomatology, a CT-scan and a MRI (Figure
Same patient as in Figure
The patient had sustained a fracture of both forearm bones treated by elastic stable intramedullary nailing 6 months before. As the surgery of nails removal was already planned, he was operated at the same time by direct open curettage of the OO, under general anesthesia and in one-day surgery. Histopathology confirmed the diagnosis of OO. There was no postoperative complication and the pain disappeared quickly two days after surgery. One month after surgery the mobility of ankle was similar to the contralateral side and limping had disappeared.
Clinical examination showed painful hip motion, limitation of hip abduction and medial rotation, and also swelling of the homolateral knee. The knee was not painful.
C-reactive protein (CRP) was less than 0.6 mg/L (normal: <0.5 mg/L), protein electrophoresis and hemogram were normal. Antinuclear factor (ANF) test,
Given the persistence of pain the patient was reviewed one month later by the rheumatologist and underwent an intra-articular methylprednisolone acetate injection with no change of symptomatology. Three weeks after the injection a new echography, radiography, and CT-scan were performed that confirmed the diagnosis of OO of femoral neck six months after the onset of pain.
After obtaining the consent of the parents, the patient underwent the radiofrequency ablation in one-day surgery.
Two days after the surgery the pain disappeared. One month later, hip joint range of motion was normal and limping had disappeared.
Intra-articular OO are often misdiagnosed as juvenile arthritis and are initially inappropriately treated. Three cases of our intra-articular OO were localized in the hip, which is the more frequent location of intra-articular OO [
Despite the improvement of the imaging techniques, diagnosis of atypical location of OO still remains a challenge. The initial erroneous diagnosis of juvenile arthritis was given in all of our cases and the delay before correct diagnosis ranged from 4 to 7 months after the onset of symptoms. In the literature, this delay is variable, ranging from 2 months to 10 years [
In our cases, radiograph was not able to give the diagnosis of intra-articular OO and echography showed aspecific joint effusion. On initial radiograph the nidus is found in only 28 to 50% of the cases due to the minimal sclerotic reaction of the trabecular bone, especially when the size of the nidus is below 3 mm [
Bone scan (scintigraphy) may orientate the diagnosis of OO. The distinctive presentation is commonly referred to as the “double density sign.” In the case of intra-articular OO, this “double density sign” is not often seen due to synovitis, osteoporosis, and hyperemia [
CT-scan is the method of choice to identify the nidus of an intra- or juxta-articular OO. The appearance on CT-scan is a round or oval low attenuation nidus surrounded by varying degrees of sclerosis. In all of our patients, this exam showed the nidus. Spouge and Thain showed that CT-scan may fail to diagnose OO when the nidus is in a cancellous bone location, due to the lack of perinidal bone sclerosis [
On MRI, the nidus is typically hypointense on T1- and T2-weighted images, with surrounding bone marrow edema and high contrast enhancement after gadolinium administration. Intra-articular lesions may demonstrate synovial thickening apparent on MRI, confirmed by contrast injection. However, precise location of the nidus may not be easy and in 35% of the cases, the nidus cannot be detected since it is often hidden by the associated perilesional edema surrounding the lesion, while in 50% of the cases, the nidus has an atypical presentation, which may lead to misdiagnosis [
All patients had a complete relief of pain after radiofrequency ablation or surgery and no recurrence was detected at the time of the last followup.
Clinicians and radiologists should be aware of the potentially confusing clinical and imaging findings associated with intra-articular osteoid osteoma.
The authors declare that there is no conflict of interests regarding the publication of this paper.