A 16-year-old boy arrived to the hospital complaining about low back pain he had been experiencing for two months. The pain got worse at night and he could find relief thanks to NSAIDs.
No history of trauma had been reported.
Laboratory findings showed increase of aspecific inflammatory markers (CRP 0,7 mg/dl, ESR 35 mm/h).
Plain radiographs of lumbosacral spine showed mild scoliosis with right-sided curvature (Figure 1a-b).
Because the patient continued to complain about low back pain, the clinicians decided to perform a gadolinium-enhanced MR, revealing intraspongious oedema of the right peduncle, as well as of the lamina and the postero-lateral part of L2 body, which was associated with soft tissues swelling (Figure 2a-b). In L2 right lamina a contrast-enhancing central lesion was visible – low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. A hypointense rim was found around the lesion in all sequences (Figure 3a-b, 4a-b).
An unenhanced CT was then performed; this showed a hypodense central core with a thin calcific rim, surrounded by sclerosis and thickening of the cortical bone of the right neural arch (Figure 5).
Thus the diagnostic hypothesis of osteoid osteoma was advanced.
After multidisciplinary discussion because of the closeness of the lesion to nervous structures, the patient was treated with a transcutaneous thermoablation with liquid protection.
After the procedure, CT and MR showed nidus disappearance and residual bone sclerosis (Figure 6a-b-c).
Osteoid osteoma is a benign bone tumour. It usually occurs in young people aged between 5-25, with 2:1 male to female ratio. Long bones of the appendicular skeleton represent the most common location of this tumour, especially when it comes to femur and tibia. It usually develops within the bone cortex [1]. The spine is involved in about 10% of the patients; the lumbar spine is most commonly affected (60%), followed by the cervical (27%) and then the thoracic spine (12%). There is a predominant involvement of the posterior elements of the vertebrae, such as spinous and transverse processes, facets, lamina and pedicles [2].
A typical lesion consists in a central nidus with variable mineralized content, surrounded by a rim of cortical thickening and by an external layer of reactive sclerosis. The nidus is usually spherical, smaller than 2 cm, and it contains a high amount of prostaglandins. These inflammatory mediators are considered responsible for the intense peritumoral reaction and the subsequent pain [3].
Plain radiographs may show a radiolucent central core surrounded by a halo of sclerosis, but in many cases they’re negative, especially when it comes to spine lesions.
CT is the best diagnostic technique: it allows to see the well-defined nidus, which has a central spot of high attenuation due to mineralized matrix. The nidus is bordered by fusiform thickening of the high-density cortical bone.
MR is usually less effective in detecting the central nidus, while it’s better suited to show the bone oedema adjacent to the lesion, as well as the surrounding soft tissues swelling and – when it’s the case - the articular involvement. The nidus has low to intermediate signal intensity on T1-weighted images and variable signal intensity on T2-weighted images, depending on the level of mineralization. The central nidus demonstrates enhancement after the administration of a contrast medium in MR, with rapid arterial phase wash-in and partial venous phase wash-out, while there is a delayed enhancement of the surrounding marrow and periosteal oedema [4, 5].
The treatment can consist in conservative management with NSAIDs, surgical excision or CT guided percutaneous radiofrequency ablation (CTgRFA) and other possible interventional radiological techniques [6].
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Osteoid osteoma
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Based on the provided CT and MR images, a lesion is observed in the posterior structures of the lumbar vertebra (such as the pedicle or lamina). It appears as a small, round or nearly round lesion with a central high density or partial calcification, surrounded by varying degrees of sclerosis and bone hyperplasia. On MRI, there is marked bone marrow edema and soft tissue edema around the lesion. Considering the patient’s back pain at night and pain relief after NSAIDs, this suggests a small, localized area of bone destruction with a significant local reaction.
The above differential diagnoses are mainly based on the lesion’s morphology, size, characteristics of nighttime pain, and the localized bone sclerosis noted on imaging.
Based on the patient’s age (16-year-old), the nighttime pain relieved by NSAIDs, the typical findings on CT showing a small central nidus with surrounding sclerosis, and laboratory results indicating only mild inflammation (slightly elevated CRP and ESR), the most likely diagnosis is Osteoid Osteoma.
1. Treatment Strategy:
2. Rehabilitation/Exercise Prescription Suggestions: Before and after treatment, especially if interventional or surgical procedures are performed, a gradual exercise program should be tailored to the patient’s condition.
This report is a reference analysis based on the available information and does not replace an in-person consultation or professional medical opinion. If you have any further questions or if your symptoms change, please seek timely medical advice and any necessary examinations.
Osteoid osteoma
