Intra-articular Osteoid Osteomas: Imaging Manifestations and Mimics.

Area of Science:

• Pediatric Orthopedics
• Musculoskeletal Radiology
• Oncology

Background:

• Osteoid osteoma (OO) is a common benign bone tumor in children, typically affecting long bone shafts.
• Intra-articular OO, often in the hip, presents with nonspecific joint pain and limited motion, leading to diagnostic delays.
• Distinguishing intra-articular OO from other joint pathologies is challenging due to subtle clinical and radiographic signs.

Purpose of the Study:

• To elucidate the distinct clinical and imaging manifestations of intra-articular osteoid osteoma in pediatric patients.
• To emphasize the importance of recognizing specific imaging features to avoid misdiagnosis and delayed treatment.
• To guide radiologists in identifying intra-articular OO and differentiating it from extra-articular lesions.

Main Methods:

• Review of clinical presentations and imaging findings (MRI, CT, bone scintigraphy, PET/CT) of intra-articular OO.
• Comparison of imaging characteristics between intra-articular and extra-articular osteoid osteomas.
• Illustration of diverse intra-articular OO manifestations.

Main Results:

• Intra-articular OO exhibits unique MRI findings, including synovitis, joint effusion, and bone marrow edema.
• CT may be insufficient for nidus visualization in intra-articular lesions, often requiring advanced imaging like PET/CT.
• Clinical symptoms are often vague, mimicking other joint conditions, contributing to diagnostic delays.

Conclusions:

• Familiarity with the specific imaging attributes of intra-articular OO is essential for accurate diagnosis.
• Timely diagnosis of intra-articular OO prevents unnecessary procedures and improves patient outcomes.
• Radiologists play a critical role in identifying intra-articular OO through awareness of its distinct presentation.