small-blue-round-cell tumor small-blue-round-cell tumor in histopathology, a small-blue-round-cell tumour (abbreviated sbrct), also known as a small-round-blue-cell tumor (srbct) or a small-round-cell tumour (srct), is any one of a group of malignant neoplasms that have a characteristic appearance under the microscope, i.e. consisting of small round cells that stain blue on routine h&e stained sections. small blue round cells of ewing sarcoma display of small round blue cells characteristic of desmoplastic small round cell tumour. these tumors are seen more often in children than in adults. they typically represent undifferentiated cells. the predominance of blue staining is because the cells consist predominantly of nucleus, thus they have scant cytoplasm. examples tumors that belong to this group are: desmoplastic small-round-cell tumour ewing sarcoma/pnet neuroblastoma medulloblastoma rhabdomyosarcoma synovial sarcoma carcinoid tumor mesothelioma small cell lung cancer wilms' tumour retinoblastoma small-cell lymphoma hepatoblastoma- only the anaplastic form has round blue cells, the more common fetal and embryonal types do not merkel cell carcinoma mesenchymal chondrosarcoma conditions mimicking sbrct endometrial stromal condensation may mimic a small-blue-round-cell tumour. endometrial stromal condensation may mimic a small-blue-round-cell tumour.