INTRODUCTION
Ewing sarcoma is the third most common bone sarcoma and the second most
common malignant bone tumor in children and young adults, with an
incidence of 0.1/100 000/year and a median age at diagnosis of 15 years.
Most cases arise in the extremities, but axial skeleton and soft tissue
origin are possible. [1] Histological diagnosis is supported by the
detection of specific gene translocations, generally resulting in
EWSR1-FLI1 fusion (EWS-RNA binding protein 1 - Friend leukemia
integration 1 transcription factor) or, more rarely, in other ETS genes
(Erythroblast Transformation-Specific) such as EWSR1-ERG fusion (ETS
Related Gene). [2] With the introduction of multiagent perioperative
chemotherapy, including vincristine, doxorubicin, cyclophosphamide,
ifosfamide and etoposide, 5-year OS increased to 65-70% in localized
disease. [1] About 25% of patients present at diagnosis with
advanced disease at diagnosis: most frequently involved sites are lung,
bone and bone marrow. For this reason, an accurate skeletal staging with
positron emission tomography (PET-CT) is mandatory and, in doubt cases,
it must be completed with bone marrow biopsy and aspirate. [3]
Five-year overall survival in patients with metastatic disease ranges
from 20 to 40% according to metastases site, with bone localizations
conferring a poorer prognosis. [4]
Moreover, Ewing sarcoma recurrence with bone marrow involvement has been
associated with very poor survival and unavoidable fatal outcome, in
contrast to patients with multiple bone metastases but no marrow
involvement [5]. High-dose ifosfamide has been recently demonstrated
to be highly effective on recurrent disease, with other active regimens
being cyclophosphamide and topotecan, temozolomide and irinotecan, and
gemcitabine and docetaxel. [6] Here we present the case of a young
male patient affected by extremity Ewing sarcoma recurring with bone
marrow infiltration causing severe pancytopenia 15 months after the end
of adjuvant chemotherapy.