CD99 and neoplasm: In Prostatic stromal sarcoma (PSS) unlike the PES, immunohistochemically, the tumour cells are widely positive for vimentin, CD56, CD99 and focally positive for synaptophysin, CD10, progesterone receptor, desmin and CD34, but negative for EMA, cytokeratin, estrogen receptor, S-100 and myoglobin[31].