Cancerous tumors composed of small cells which stain blue
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 malignantneoplasms that have a characteristic appearance under the microscope, i.e. consisting of small round cells that stain blue on routine H&E stained sections.
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.[1][2]