Management of Recurrent Osteoid Osteoma: Case Report

Abstract

Osteoid osteoma is a benign bone tumor accounting for 10% of all benign bone tumors and 2 to 3% of all primary bone tumors. Pain is the predominant presenting symptom demanding medical attention. Radiofrequency ablation has become the standard line of treatment due to its high clinical success rate. Although it is highly effective, the recurrence rate is estimated to be in the range of 7 to 16.3%, with younger individuals having higher recurrence rates. We report a unique case of recurrent osteoid osteoma with a metachronous lesion in a female child for which radiofrequency ablation of both the lesions was performed, which proved to be effective.

Keywords

recurrent osteoid osteoma - radiofrequency ablation - CT-guided ablation

Introduction

Osteoid osteoma is a benign bone tumor accounting for 10% of all benign bone tumors[1] and 2 to 3% of all primary bone tumors.[1] [2] It mostly affects patients in the age group of 5 to 20 years.[2] Pain is the predominant presenting symptom demanding medical attention. Radiofrequency ablation (RFA) has become the standard line of treatment due to its high clinical success rate. Although it is highly effective, the recurrence rate is estimated to be in the range of 7 to 16.3%,[3] [4] with younger individuals having higher recurrence rates.[3] We report a unique case of recurrent osteoid osteoma with a metachronous lesion in a female child for which ablation of both the lesions was performed, which proved to be effective.

Case Report

A 6-year-old girl presented with pain in the right thigh for a duration of 3 months. The pain was insidious in onset and gradually progressive, which aggravated during the night and was typically reduced with an anti-inflammatory medication, ibuprofen 100 mg. She was a known case of osteoid osteoma of the right femur for which she had previously undergone RFA of the lesion 1 year back at a different institution. She was asymptomatic for a period of 9 months, following which the symptoms recurred. Computed tomography (CT) of the lower limbs was performed, which showed two small ovoid lucent lesions at the medial aspect of meta-diaphyseal region of the neck and the proximal shaft of the right femur ([Fig. 1]). The lesions showed a reactive sclerotic rim. The imaging features were typical of recurrent osteoid osteoma. A comparison of previous images done at a different institute with the CT scan done at our institution showed that the lesion near the shaft of the femur could be the previously targeted lesion that was persistent in the recent scan done at out institute. This could be the recurrent lesion. The more proximal lesion at the meta-diaphyseal region of the neck seemed to be a new lesion that was not present in the previous CT scan.

Fig. 1 Coronal reformatted image of the right femur showing two ovoid lucent lesions (arrows) with a sclerotic rim on the medial aspect of the meta-diaphyseal regions of the neck and the proximal shaft.

RFA was planned for both the new lesion and the recurrent lesion. She was admitted a night before the procedure. Informed consent was obtained from the parents. With overnight fasting and under antibiotic coverage, CT-guided planning was done under general anesthesia. The distal lesion was approached from the lateral aspect of the thigh. Bone was drilled with an 11-gauge bone biopsy coaxial needle. Through its cannula, a 13-gauge biopsy needle was introduced, and a sample was obtained. Later, with an 11-gauge biopsy needle in place, the tip of 170-gauge radiofrequency (RF) needle was precisely placed within the nidus of the lesions ([Fig. 2]). In a similar manner, the proximal lesion was also sampled and later ablated with an RF needle. The lesions were sequentially ablated with the use of an RF generator (Medtronic). Ablation was performed at the target temperature of 90°C for a period of 5 minutes each. Postprocedural care included sterile dressing and adequate analgesia.

Fig. 2 (A) Axial image of the distal osteoid osteoma (arrow) at the medial aspect of the proximal shaft of the right femur and (B) radiofrequency (RF) needle positioning (arrow) at the nidus. (C) Axial image of the proximal osteoid osteoma (arrow) at the neck of the right femur and (D) RF needle positioning (arrow) at the nidus.

The histopathological analysis confirmed both the lesions to be osteoid osteoma ([Fig. 3]). The child remains asymptomatic at 6 months of follow-up.

Fig. 3 Trabeculae of immature woven bone (white arrow) compose the nidus of the lesion with a rim of occasional osteoblasts and fibrous connective tissue (black arrow) forming the sclerotic rim.

Discussion

Osteoid osteoma is a benign bone tumor most commonly affecting the metaphysis or the diaphysis of the long bones of the lower limbs like the femur and tibia.[1] It is composed of a central nidus with an outer sclerotic bone. The central nidus, which usually measures less than 1.5 cm, is made up of vascularized tissue with intertwined osteoid. They have been shown to release high amounts of prostaglandins, which increase the blood flow into the lesion. This in turn is responsible for causing pain.[2] Pain is the predominant symptom in patients, and it aggravates in the night and is alleviated with nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit the synthesis of prostaglandins.

Osteoid osteoma can be classified based on the location within the bone. It can be classified into subperiosteal, intracortical, endosteal, and intramedullary, of which intracortical osteoma is the most common type.[2] They usually occur at the metaphysis or diaphysis of the long bones. The degree of sclerosis can vary. Children are shown to have a more sclerotic rim compared with adults.[2]

CT is the modality of choice for diagnosing osteoid osteoma. Osteoid osteoma typically has a well-define round or ovoid soft tissue attenuating or lucent area composed of the central nidus surrounded by a dense sclerotic rim. This nidus shows enhancement on administration of a contrast agent.[2] On magnetic resonance imaging (MRI), the central nidus shows low to intermediate signal intensity on T1-weighted imaging and high signal intensity on T2-weighted and short tau inversion recovery (STIR) imaging. The sclerotic rim shows low signal intensity on T1- and T2-weighted imaging.

The natural history of osteoid osteoma can be varied. Although few of them undergo spontaneous resolution, many of them require medical, surgical, or ablative intervention. Medical management with salicylates and NSAIDs can be limited due to decreased effect over time and low pain tolerance in children. Conventional surgical method of en bloc excision of a nidus potentially bears risk of pathologic fractures, scar formation, and recurrences in cases of difficult localization of the nidus.[5] Surgical excision may cause impairment of the growth process and joint mobility in children with lesions near the epiphyseal regions. CT-guided percutaneous ablative methods surpass these disadvantages and thus forms a strong alternative by being minimally invasive. CT-guided RFA has proved to be a safe and highly effective procedure.[6] Typically, a single RF probe is aimed at the core of lesions measuring less than 10 mm and multiple needle placements are used for sufficient tumor ablation in lesions measuring greater than 10 mm.[6] It is shown to have high clinical success rates of 89 to 95%.[7]

Children are at a higher risk of recurrences of osteoid osteoma compared with other bone tumors. This has been attributed to the process of increased bone turnover in children.[8] Factors like tumor dimension (maximum tumor length >10 mm), young age (<13 years), and female gender have been significantly associated with symptomatic recurrence.[8] In our case, the patient was a young girl. The RF therapy recurrence rate is estimated to be around 7% overall, with younger individuals having greater rates.[3] Multiple osteoid osteomas in the same patient are rare and are seen in less than 1% of reported cases.[9] RFA is a safe and promising method for treating patients with recurrence of osteoid osteoma.

Conclusion

In conclusion, our case is unique for reasons like multiple lesions in the neighboring location, with histological confirmation. Second, it is unique due to recurrence of symptoms with a metachronous appearance of a new lesion and simultaneous use of RFA for both the lesions for treatment. Our case suggests simultaneous ablation of the new lesion as well as the previously treated lesion to avoid further symptomatic relapses. We aim to highlight that there needs to be a high suspicion for recurrence in a younger individual who presents with classical symptoms of osteoid osteoma even after treatment.

Conflict of Interest

None declared.

• References

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Publication History

Article published online:
10 February 2025