Abstracts

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E1275. Non-traumatic Pediatric Hip Pain: Not the Usual Suspects
Authors
  1. Samuel Madson; Department of Radiology, San Antonio Military Medical Center
  2. Doug Byerly; Department of Radiology, San Antonio Military Medical Center; Uniformed Services University of the Health Sciences
  3. Anthony Zarka; River City Imaging Associates, Christus Health
Background
Hip pain is a common cause for presentation of children both in clinic and emergency departments, and can be a sign of serious underlying pathology. Literature supports that hip etiologies should be considered any time pediatric patients present with limping, or complaints of knee or thigh pain. Although the differential is broad, providers often resort to thinking about the most common diagnosis: trauma, septic joint, avascular necrosis, or slipped capital femoral epiphysis (SCFE). Although these common etiologies are often encountered in the appropriately aged patient, the radiologist must remain vigilant and be able to distinguish them from other less common yet more serious etiologies. The goal of this presentation is to review the magnetic resonance imaging (MRI) features of the less common causes of non-traumatic hip pain through a case based format. Focus will be on distinguishing features when possible, and will portray overlapping features when necessary, which when applied can help providers include the appropriate diagnosis in the differential.

Educational Goals / Teaching Points
Using case examples, we will review the MRI features of the following: septic arthritis, acute leukemia, metastatic disease, osteoid osteoma, osteomyelitis, atypical osteomyelitis (Bartonella), chronic recurrent multifocal osteomyelitis (CRMO), juvenile arthritis, Langerhans cell histiocytosis (LCH), intra-articular osteochondroma, pyomyositis, Ewing sarcoma, synovial sarcoma, and aneurysmal bone cyst (ABC). Focus will be on utilizing clinical presentation, location, and differentiating imaging features to provide an appropriate differential when a specific diagnosis cannot be made. Provide guidance on when to suspect and how to diagnose these less common, yet more serious etiologies of hip pain to decrease delays in diagnosis and improve patient outcomes.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Radiographs are generally the initial imaging modality performed, and essential for evaluation of bony pathology and identifying key features which may indicate further imaging is necessary. Computed tomography (CT) is often complementary to radiographs with both radiographs and CT providing information regarding tumor matrix, periostitis, cortical destruction, and the extent of local tissue involvement. MRI provides excellent soft tissue contrast, enables evaluation of marrow processes, and has the benefit of lack of ionizing radiation. MRI is a powerful tool to further characterize lesions and often can lead to either diagnosis or narrow the differential prior to pathologic confirmation if necessary.

Conclusion
The differential diagnosis for non-traumatic pediatric hip pain is broad. While a few diagnoses constitute the majority of presentations, some less common etiologies are more sinister. It is important to be familiar with the presentations and distinguishing features of these rare disease process to ensure timely diagnosis, limit unnecessary treatment, and improve patient outcomes. This review can be used as a framework to formulate differentials and guide further treatment/management decisions in the child with non-traumatic hip pain.