GANGLION-CELLS IN EWINGS-SARCOMA FOLLOWING CHEMOTHERAPY - A CASE-REPORT

A case of Ewing's sarcoma of the bone, arising in the right radius of a 12-year-old girl, which showed unique histologic features after pre- operative treatment, is reported. The light microscopic features of a biopsy sample were those of a small round cell tumor showing positive immunoreaction with antibodies against the product of the MIC 2 gene ( 013), neuron-specific enolase, neurofilament, and synaptophysin, but n o morphological differentiation. The patient received combined intensi ve multi-drug chemotherapy and radiation before surgery. Examination o f the surgical specimen showed that the tumor was less cellular than t hat in the biopsy specimen, and was composed mainly of loosely texture d large cells mimicking ganglion cells, occasionally forming Homer-Wri ght rosettes. An immunohistochemical study revealed that neural differ entiation was enhanced. Immunoreactivity for Leu-7 also became positiv e. Although the patient underwent postoperative chemotherapy, she died of multiple lung and bone metastases 30 months after the diagnosis. A utopsy showed that metastatic foci were made up of densely packed smal l round cells like those seen in the biopsy samples, but associated wi th prominent Homer-Wright rosettes, To the authors' knowledge, this is the first report of a tumor being replaced almost entirely by ganglio n cells after pre-operative chemotherapy and radiotherapy.