Discussion:
Ewing sarcoma is an aggressive malignant primary tumor of bones or soft tissues that usually occurs in adolescents and young adults (usually in the second decade of life). It is named after James Ewing who was the first one to describe the condition in 1921. Males are three times more likely to get the disease than females and it occurs in Whites more than it does in any other race like Hispanics and Africans. Up to quarter of patients present with metastases at the time they receive their diagnosis and it such case it is usually characterized by resistance to intensive therapy. Treatment of Ewing’s sarcoma is dependent on whether the disease is localized or metastatic, but the general theme for treatment is a multimodal approach to the sarcoma including surgical intervention, radiotherapy as well as chemotherapy and a multidisciplinary team is usually involved in treatment. While this treatment approach is very effective for localized disease, metastatic disease prognosis remains poor (1-3).
Many cases of Ewing’s sarcoma can be diagnostically challenging in terms of both the clinical presentation and their radiographic assessment with osteomyelitis being the most notable disease to be confused with it. Other disease entities have also been reported to be confused with Ewing’s sarcoma as well. Clinically, constitutional symptoms can occur in both conditions. The presence of an elevated temperature and bone pain can occur in both Ewing’s sarcoma and osteomyelitis along with increased markers of inflammation (4).
Features favoring Ewing’s sarcoma over osteomyelitis on radiography include presence of a Codman triangle, a periosteal reaction, a soft tissue mass or merely involvement of the bone metaphysis or adjacent joints. While Ewing’s sarcoma is generally characterized on magnetic resonance imaging (MRI) by permeative cortical involvement with soft tissue mass, osteomyelitis has a serpiginous tract involvement. Osteomyelitis occurred more often in African Americans than Ewing’s sarcoma did (5).
That is being mentioned, MRI findings can still be inconclusive; thus, a biopsy of the lesion should be performed to confirm or rule out the diagnosis of Ewing’s sarcoma. Special attention regarding how to perform the biopsy should be taken and it should be performed cautiously to prevent hematoma formation and, most importantly, infliction of the adjacent joints or neurovascular bundles with tumor cells in case of Ewing’s as affected structures must be removed in such case. Therefore, whenever there is a possibility of Ewing’s sarcoma, the biopsy should be performed with consultation of an oncological orthopedic department at a sarcoma specialized center as an inappropriate biopsy intake has been reported to result in large areas removal and amputations which could have otherwise been prevented. Marking the site where the biopsy was taken can help with its recognition in surgery after neoadjuvant chemotherapy (4,6).
Confirmation of the disease should be combined with diagnostic modalities to determine whether the disease is localized or has metastasized to other body organs. The most widely acceptable and currently used is the combination of whole-body MRI and chest CT. Combination of PET and MRI scans is getting more popularity (7).
Alexandre Arkader et al. suggested four reasons to miss Ewing’s sarcoma diagnosis and establishing another diagnosis which involve an atypical site of the lesion, inadequate biopsy to confirm the disease histologically, absence of malignant features on imaging as well as having a low index of suspicion for the lesion (8).
Histologically, Ewing’s sarcoma is characterized by solid growth pattern of small cells that have round nuclei and an abundant glycogen deposition in almost half of cases. Glycogen deposition results in cells being periodic acid–Schiff (PAS) stain positive cells. Cells with larger nuclei that are PAS negative characterize the atypical variant of Ewing sarcoma (9,10).
After introduction of the multidisciplinary approach to treatment of Ewing sarcoma with the combination of surgery, chemotherapy and radiation, the, survival rate has increased to over 50%. Not only that, but even the surgical approach to the tumor has shifted from limb amputation to limb salvage surgery.
In this case we report a case of a 9-year-old girl with Ewing’s who was initially thought to have osteomyelitis. As part of osteomyelitis management, an attempt of drilling of the cortex has paved the way for the tumor to extend to all thigh compartments. The limb was beyond salvage at time of presentation. Disarticulation was the final result of the course of the misdiagnosis. Here, the primary surgeon relied on their clinical judgment and had a low level of suspicion.
This case has been reported in line with the SCARE criteria (11).