Subperiosteal osteoid osteoma in the talar neck

Clinical History

An 18-year-old man presented with a nocturnal pain of the left ankle.

Imaging Findings

The patient had been enduring a debilitating nocturnal pain of the left ankle for the past four months, and had obtained no relief from steroidal anti-inflammatory drugs. A clinical examination was done, which showed tumefaction of the ankle with limited mobility. A conventional radiography analysis showed a solitary rounded lytic zone, which had geographical contours, and a narrow transitional zone with the healthy bone (Fig. 1). The ultrasonography examination found the presence of intra-articular fluid associated with synovial thickening (Fig. 2). We then suspected a tumoral or a synovial process. The MRI studies showed the presence of a subperiosteal lesion in the talar neck, which had a decreased signal intensity on T1, moderately increased signal on T2, surrounded by a marginal osteosclerosis with decreased intensity on the different sequences, and associated with a central gadolinium- enhancement (Fig. 3). A CT scan showed the presence of a subperiosteal lytic lesion with a partially calcified central nidus surrounded by a marginal osteosclerosis (Fig. 4). The patient underwent surgical excision.

Discussion

Osteoid osteoma is a benign osteogenic tumour that occurs in the young adult. Its localization on short and flat bones is rare. A juxta-articular osteoid osteoma arising around the ankle is unusual (1). Tumors arising on the neck of the talus will commonly produce symptoms mimicking monoarticular arthritis or trauma (1). In the diagnosis of an osteoid osteoma, a history of the relief of pain with the use of aspirin is an important consideration. Plain radiographs are useful. Fine-cut computed tomography scanning or magnetic resonance imaging procedures are the best studies for making a definitive diagnosis (2). The CT scan shows subperiosteal hypodensity in the talar neck, with or without a central calcification corresponding to the nidus. It shows an absence of periosteal reaction which is typical in osteoid osteoma of the long bones. The MRI examination demonstrates a decreased intensity on T1, moderately increased signal on the T2-image of the lesion, surrounded by a marginal osteosclerosis with decreased intensity on the different sequences. A central gadolinium hold, represents the osteoid osteoma. It is associated with synovial thickening, intra-articular extrusion, and a marked inflammatory reaction in bone (3,4,5). The scintigraphy tehnique represents an unspecific but sensitive method of diagnosis in the early stages. The osteoid osteoma is visible as a "hot spot" or, in the subperiosteal type, as a diffuse accumulation. Once the diagnosis is confirmed, percutaneous computed tomography-guided thermocoagulation is the most frequently used therapy. En bloc resection and an autogenous bone graft can cure the disorder(5). Localization by computed tomography-guided needle placement or intraoperative radionuclide scanning is recommended to find the lesion for excision (5). The technique of interstitial laser photocoagulation is a safe and cost-effective method of osteoid osteoma treatment (5).

Differential Diagnosis List

Final Diagnosis

Osteoid osteoma in the talar neck.

URL:	https://www.eurorad.org/case/3142
DOI:	10.1594/EURORAD/CASE.3142
ISSN:	1563-4086