Small round cell tumours
Small round cell tumours (SRCT), also small round blue cell tumours (SRBCT), are a group of tumours that have a similar histologic appearance.
It is a group of tumours that is seen more often in childhood than adulthood.
DDx:[1]
- Neuroblastoma.
- Wilms tumour (AKA nephroblastoma).
- Alveolar rhabdomyosarcoma.
- Ewing sarcoma/PNET - this entity is dealt with in the bone tumours article.
- Lymphoma - large cell lymphomas, e.g. diffuse large B cell lymphoma, anaplastic large cell lymphoma.
- Retinoblastoma.
- Hepatoblastoma.
- Desmoplastic small round cell tumour (DSRCT).
Memory device: 4 -blastoma (hepato-, neuro-, nephro-, retino-), PNET/Ewing sarcoma (medulloblastoma), DSRCT, lymphoma, alveolar rhabdomyosarcoma.
Microscopic
Features:
- Sheets of cells, very cellular.
- Small cells ~ 2X RBC diameter.
- Scant cytoplasm.
- Coarse chromatin.
- +/-Nucleolus. (???)
- +/-Vascular.
Tabular comparison
Adapted from Thorner:[2]
| Tumour | Key histologic features | History | Key IHC / special stains |
| Hepatoblastoma | fetal hepatocytes (~ 1:3 NC ratio, eosinophilic cytoplasm) | liver | AFP |
| Neuroblastoma | nests, thin fibrovascular septae, lymphocytes, ganglion-like cells (prominent nucleolus), neurophil (eosinophilic, fluffy, finely vacuolated) | adrenal gland, sympathetic chain; usu. < 3 years old | NB-84+, NSE+, S100- |
| Nephroblastoma (Wilms tumour) | triphasic - (1) blue cells (blastema), (2) spindle cells (stroma), (3) tubular structures (epithelial) | kidney lesion, various syndromes | WT-1+ |
| Retinoblastoma | Flexner-Wintersteiner rosette (rosette with empty centre (donut hole))[3] | eye lesion; +/-RB1 gene mutations (familial) | |
| Medulloblastoma | Homer-Wright rosettes (rosette with a meshwork of fibers (neuropil) at the centre)[3] | +/-nevoid basal cell carcinoma syndrome | |
| Ewing sarcoma/PNET | clear cytoplasm (glycogen) | bone lesion, adolescents | PAS+/PASD-, CD99 diffuse membranous |
| Rhabdomyosarcoma, alveolar | rhabdomyocytes (eosinophilic cytoplasm +/-cross striations (uncommon), eccentric nucleus) | adolescents, young adults; often mets at presentation | "DAM" = desmin, actin, myogenin |
| Rhabdomyosarcoma, embryonal | rhabdomyocytes (elongated/cigar-shaped cells, eosinophilic cytoplasm +/-cross striations, eccentric nucleus), nests with rounded border | <10 years old; usu. localized | "DAM" = desmin, actin, myogenin |
| Desmoplastic small round cell tumour (DSRCT) | nests with "jigsaw" border | peritoneum (abdomen or plevis); male > female; locally invasive | keratin+, EMA+, desmin+ !!! |
| Small cell carcinoma | stippled chromatin, nuclear moulding | adults, smokers | synaptophysin, chromogranin, CD56, keratins |
| Lymphoma (large cell) | dyscohesive cells, ~2x normal (resting) lymphocyte, nucleolus | lymphadenopathy (???) | CD45 |
See also
References
- ↑ URL: http://www.thedoctorsdoctor.com/diseases/small_round_blue_cell_tumor.htm. Accessed on: 2 July 2010.
- ↑ PST. 14 February 2011.
- ↑ 3.0 3.1 Wippold FJ, Perry A (March 2006). "Neuropathology for the neuroradiologist: rosettes and pseudorosettes". AJNR Am J Neuroradiol 27 (3): 488–92. PMID 16551982.