We report the case of a patient in whom the diagnosis of Ewing sarcoma arising 
from a soft tissue was made after successful treatment of diffuse large B-cell 
lymphoma. A 65-year-old woman presented with a rapidly growing mass in her left 
scapular region 8 years after successful chemotherapy with the cyclophosphamide, 
hydroxydaunomycin hydrochloride, vincristine, prednisolone regimen for diffuse 
large B-cell lymphoma. Computed tomographic examination and magnetic resonance 
imaging of the thorax revealed an intramuscular tumour measuring 40 mm in size 
in the left scapular region. Histopathological examination of an open biopsy 
specimen revealed a small round cell tumour that showed positive staining for 
CD99. Fluorescence in situ hybridization showed a split signal by a break-apart 
probe for the EWS gene in chromosome 22q12. Reverse transcriptase-polymerase 
chain reaction confirmed the expression of EWS-FLI1 fusion transcripts. Based on 
these findings, the patient was diagnosed as having secondary Ewing sarcoma. 
Despite adjuvant chemotherapy, however, she died of pulmonary metastases 2 years 
after the diagnosis of Ewing sarcoma. Therapy-related haematological 
malignancies with balanced translocations have been reported previously. A 
mechanism similar to that underlying the development of secondary malignancy 
might explain the occurrence of this solid cancer.