Misdiagnosis of Ewing’s sarcoma of the ilium at the pelvis X-ray

Abstract

DiVerential diagnosis of coxalgia in young patients requires that transient hip synovitis (also known as “irritable hip”) is distinguished from septic arthritis, Legg-Calve-Perthes disease (an idiopathic avascular osteonecrosis of the femoral epiphysis), slipped capital femoral epiphysis, and pyomyositis. Transient hip synovitis recurs in up to 15% of children and may aVect the same or opposite hip [1]. Juvenile idiopathic arthritis might frequently involve the hip joint, resulting in functional impairment prior to the closure of the proximal femoral capital epiphysis [2]. X-ray Wlms, ultrasonography, and magnetic resonance imaging (MRI) are the most common instrumental tools used to assess the pediatric hip, but false negative results may occur and clinical correlation is necessary. We report the case of a 12-year-old girl who presented left hip pain, Wrstly treated with paracetamol with partial success. The patient was then admitted in a Wrst hospital for the persistent symptom: clinical examination showed restricted internal and external rotation of left hip, altered gait, and mild fever. Coxo-femoral echography showed a mild nonspeciWc left hip eVusion, suggesting the diagnosis of transient synovitis, which was treated with ibuprofen for 15 days. Pain remission was total, but in the following 3 months hip pain reappeared occasionally, though it was related to patient’s obesity (weight 62 kg, BMI 34.5). Pelvis X-ray was reported as normal at this Wrst reading. A new admission in a second hospital showed these laboratory results: Hb 10.4 g/dl, white blood cell count 12,690/ mm, platelet count 339,000/mm, erythro-sedimentation rate 73, C-reactive protein 62 mg/l, lactate dehydrogenase 429 IU/l, ferritin 159 ng/dl, and alkaline phosphatase 139 IU/l. Quantiferon test was negative. Contrast-enhanced MRI of the hip revealed an unexpected large lytic lesion in the left iliac wing, destructing the internal cortical zone (Fig. 1). Histopathology of the lesion revealed a malignant round-cell tumor consistent with Ewing’s sarcoma (ES). As a result of this diagnosis, we compared the antero-posterior view of pelvis X-ray containing the tumor area (Fig. 2) with MRI scans and found that the same osteolytic lesion in the iliac bone was misdiagnosed as a meteoric bowel distention. The sharp and clearly deWned margins without motheaten lesions might have contributed to the initial wrong false negative diagnosis. ES is the second most common primary malignant bone neoplasm in children and adolescents, accounting for approximately 10% of malignant bone tumors [3]. Frequently ES is located in the pelvis, and iliac bone is frequently involved [4]. ES of the ilium mimicking sacroiliitis has been reported [5]. Clinically ES initial symptom may be confused with infectious or rheumatologic diseases, and the classic radiological presentation of an intramedullary lesion with aggressive permeative or moth-eaten bone destruction on plain radiographs may not be the rule [6]. The value of plain Wlms of this area is compromised by the anatomy of the iliac bone and by the overlying structures; F. De Maddi · P. Siani Department of Pediatrics, Cardarelli National Hospital, Via A. Cardarelli 9, 80131 Naples, Italy