Solitary Epiphyseal Enchondroma of the Proximal Femur in a 23-Month-Old Girl Cristina Ojeda-Thies, MD, Nuria Bonsfills, MD, PhD, and Javier Albin ˜ana, MD, PhD Abstract: A 23-month-old girl was referred to us because of a right leg limp for 10 days that had not improved despite anti-inflammatory treatment and that did not show signs of infection. Upon examination, gait was in abduction and external rotation of the hip. Plain radiographs showed a solitary lucent lesion of the posteroinferior two thirds of the epiphysis that was hyperintense on T2-weighted magnetic resonance scanning images. We approached the proximal femoral epiphysis using the Btrapdoor[ technique and excised the lesion by curettage and iliac crest graft. Histologically, the lesion was diagnosed as an enchondroma. We discuss the main causes of lucent epiphyseal lesions in children. Finally, we review the literature on previous reports of patients with solitary epiphyseal enchondromas. Study Type: Case report. Level of Evidence: Level V. Key Words: enchondroma, epiphyseal tumor, trapdoor procedure, femoral head (J Pediatr Orthop 2008;28:565Y568) T here are very few reports of solitary lucent epiphyseal lesions in children, most commonly as part of articles discussing specific pathological processes. These lesions may appear because of infection or a variety of tumoral conditions. Although it is well known that some entities such as the chondroblastoma can imply the epiphysis, others have been rarely mentioned. In addition to its diagnostic challenge, these lesions may also be complex to treat because of their anatomical location, especially among intraarticular epiphyses such as the hip or shoulder. We present a case of solitary enchondroma of the proximal femoral epiphysis in a 23-month-old girl. We shall also review the previously published reports of epiphyseal enchondromas in skeletally immature patients and discuss some other causes of lucent epiphyseal lesions in children. CASE REPORT A 23-month-old girl was referred to us from the pediatric emergency department, consulting because of right leg limping for more than 10 days that had not improved despite treatment with rest and ibuprofen. She had not had fever or any recent infections, and she seemed happy and active, without any other symptoms. Upon examination, her gait was in abduction and external rotation of the affected leg, with pain at passive adduction and internal rotation. There was no limitation of the range of motion, and no contractures were observed. Ultrasound of the affected hip revealed a homogeneous joint effusion and thickening of the synovium. On plain radiographs, a round lytic lesion with well-defined borders and with perilesional radiodensity that occupied the posterior and inferior two thirds of the femoral epiphysis was evident (Fig. 1). Apparently, radiographs performed at an earlier age had not revealed any abnormalities. Magnetic resonance imaging showed a round lesion, with a high signal intensity suggestive of hyaline cartilage on T2-enhanced images. In T1-enhanced images, the lesion demonstrated an inter- mediate signal intensity with a surrounding ring of lower intensity (Fig. 2). Presuming the lesion was a chondroblastoma, it was decided to excise the tumor by a direct approach. The proximal femoral epiphysis was approached using the Btrapdoor[ technique through an anterolateral Salter approach of the hip, as described by Ko et al 1 (Fig. 3); it revealed a pale grayish mucinous area in the posteroinferior portion of the epiphysis that was excised by curettage. The gap was filled with autologous iliac cancellous bone graft. The surgical instrumentation was completely exchanged before grafting. After surgery, the hip was immobilized in a spica cast for 3 weeks and with an abduction orthosis for another 6 weeks. Follow-up reviews showed satisfactory integration of the graft, and at the 18-month follow-up, the patient is asymptomatic and has a range of motion symmetric to the unaffected hip (Fig. 4). Pathological examination of the lesion showed a mass of hypercellular cartilage permeated with blood vessels without significant atypia or mitoses, and with a few dispersed binucleated chondrocytes. The specimen did include some areas of healthy bone and hyaline cartilage at its margins. The lesion was diagnosed as a solitary epiphyseal enchondroma (Fig. 5). DISCUSSION An acute limp in the child implies an underlying pathology that causes disruption of the standard gait pattern and is a frequent symptom of consult in the pediatric emergency department; the challenge for the physician is to identify this pathology. 2,3 The cause of a limp can range from something as serious as septic arthritis to something as minor as transient synovitis, also including tumors, traumatic disorders, stress fractures, and so on. Considering tumoral conditions, several entities may manifest as a solitary lucent lesion of the bone; in the workup of these lesions, one must address patient age, lesion size, location, multiplicity, matrix, bone reaction, and in extra- articular lesions, periosteal reaction. 4Y6 Very few lesions tend to arise in the epiphysis, even less before the physis closes. The chondroblastoma 7,8 is one of the very few tumors that arise here before the physis closes. ORIGINAL ARTICLE J Pediatr Orthop & Volume 28, Number 5, July/August 2008 565 From the Pediatric Orthopedics Unit, Department of Traumatology and Orthopedic Surgery, Hospital Universitario La Paz, Madrid, Spain. None of the authors received financial support for this study. Reprints: Javier Albin ˜ana, MD, PhD, Pediatric Orthopedics Unit, Department of Traumatology and Orthopedic Surgery, Hospital Universitario La Paz, Paseo de la Castellana, 261, 28046 Madrid, Spain. E-mail: jalbinana.hulp@ salud.madrid.org. Copyright * 2008 by Lippincott Williams & Wilkins Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.