Abstract：
Osteoid osteoma (OO) is the third most prevalent benign bone neoplasm in children. Although it predominantly affects the diaphysis of long bones, OO can assume an intra-articular location in the epiphysis or the intracapsular portions of bones. The most common location of intra-articular OO is the hip joint. The presentation of intra-articular OOs often poses a diagnostic enigma, both from clinical and radiologic perspectives. Initial symptoms are often vague and nonspecific, characterized by joint pain, stiffness, and limited range of motion, which frequently contributes to a delayed diagnosis. Radiographic findings range from normal to a subtle sclerotic focus, which may or may not have a lucent nidus. In contrast to their extra-articular counterparts, intra-articular lesions have distinct features at MRI, including synovitis, joint effusion, and bone marrow edema-like signal intensity. While CT remains the standard for identifying the nidus, even CT may be inadequate in visualizing it in some cases, necessitating the use of bone scintigraphy or fluorine 18-labeled sodium fluoride PET/CT for definitive diagnosis. Radiologists frequently play a pivotal role in suggesting this diagnosis. However, familiarity with the unique imaging attributes of intra-articular OO is key to this endeavor. Awareness of these distinctive imaging findings of intra-articular OO is crucial for avoiding diagnostic delay, ensuring timely intervention, and preventing unnecessary procedures or surgeries resulting from a misdiagnosis. The authors highlight and illustrate the different manifestations of intra-articular OO as compared with the more common extra-articular lesions with respect to clinical presentation and imaging findings. ©RSNA, 2024 Supplemental material is available for this article.
摘要：
骨样骨瘤（OO）是儿童第三大最常见的良性骨肿瘤。虽然它主要影响长骨的骨干，OO可以在骨的骨phy或囊内部分中占据关节内位置。关节内OO的最常见位置是髋关节。关节内OO的出现通常会引起诊断之谜，从临床和放射学的角度来看。最初的症状通常是模糊和非特异性的，以关节痛为特征，刚度,和有限的运动范围，这通常有助于延迟诊断。影像学检查结果范围从正常到细微的硬化病灶，可能有也可能没有发光的Nidus。与他们的关节外对应物相比，关节内病变在MRI上有明显的特征，包括滑膜炎,关节积液,和骨髓水肿样信号强度。虽然CT仍然是识别病灶的标准，在某些情况下，即使是CT也可能不足以可视化，需要使用骨闪烁显像或氟18标记的氟化钠PET/CT进行明确诊断。放射科医生经常在提出这种诊断中起关键作用。然而,熟悉关节内OO的独特成像属性是这项工作的关键。意识到关节内OO的这些独特的影像学发现对于避免诊断延迟至关重要。确保及时干预，并防止因误诊而导致不必要的程序或手术。作者强调并说明了关节内OO的不同表现，与更常见的关节外病变相比，在临床表现和影像学发现方面。©RSNA,2024补充材料可用于本文。
