A radiation-related second primary gastrointestinal stromal tumor in the bladder

A 69-year-old man underwent 78 Gy/39 Fr of intensity-modulated radiation therapy for prostate cancer.Seven years after radiotherapy,a nonpapillary bladder tumor was identified.Transurethral resection of the bladder tumor was performed,and the pathological diagnosis was spindle cell sarcoma.Immunostaining revealed KIT^(-),DOG1^(++),CD34^(-),Actin^(++),Cytokeratin^(-),Desmin^(-),S100 protein^(-),and Vmentin^(++).No tumor recurrence was observed until 17 months after tumor resection.DOG1 is strongly and specifically expressed in gastrointestinal stromal tumors.This was a rare case of bladder gastrointestinal stromal tumor as a radiation-related second primary tumor.