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.
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.
Tumors that belong to this group are:
- Desmoplastic small-round-cell tumour
- Ewing's Sarcoma/PNET
- Synovial sarcoma
- Carcinoid tumor
- 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.
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- Chen QR, Vansant G, Oades K, et al. (February 2007). "Diagnosis of the small round blue cell tumors using multiplex polymerase chain reaction". J Mol Diagn. 9 (1): 80–8. doi:10.2353/jmoldx.2007.060111. PMC . PMID 17251339.
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