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).