Small round cell tumours

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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][2]

Others:

Memory device: 4 -blastomas (hepato-, neuro-, nephro-, retino-), PNET/Ewing sarcoma (medulloblastoma), LADSSS (lymphoma, alveolar rhabdomyosarcoma, DSRCT, small cell carcinoma, small cell osteosarcoma, synovial sarcoma).

Microscopic

Features:

  • Small cells ~ 2X RBC diameter - key feature.
  • Scant cytoplasm/high NC ratio.
  • Sheets of cells, very cellular.
  • Coarse chromatin.
  • +/-Nucleolus; usu. not prominent.
  • +/-Vascularity.

Tabular comparison

Adapted from Thorner:[3]

Tumour Key histologic features History Key IHC /
special stains
Hepatoblastoma fetal hepatocytes (~ 1:3 NC ratio, eosinophilic cytoplasm) liver lesion, usu. < 3 years old AFP
Neuroblastoma nests, thin fibrovascular septae, lymphocytes, ganglion-like cells (prominent nucleolus), neuropil (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 (e.g. Beckwith-Wiedemann syndrome[4]) WT-1+
Retinoblastoma Flexner-Wintersteiner rosette (rosette with empty centre (donut hole))[5] eye lesion; +/-RB1 gene mutations (familial)
Medulloblastoma Homer-Wright rosettes (rosette with a meshwork of fibers (neuropil) at the centre)[5] +/-nevoid basal cell carcinoma syndrome; must arise in cerebellum
Ewing sarcoma/PNET clear cytoplasm (glycogen) bone lesion, adolescents PAS+/PASD-, CD99 diffuse membranous
Alveolar rhabdomyosarcoma alveolar-like spaces (small blue cells line spaces supported by fibrous tissue), rhabdomyoblasts (eosinophilic cytoplasm, +/-cross striations (uncommon), eccentric nucleus, +/-elongated/cigar-shaped cells (uncommon)) adolescents, young adults; often mets at presentation "DAM" = desmin, actin, myogenin
Embryonal rhabdomyosarcoma§ nests with rounded border, rhabdomyoblasts (+/-elongated/cigar-shaped cells, eosinophilic cytoplasm, +/-cross striations, eccentric nucleus) <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 nuclear moulding, stippled chromatin adults, smokers synaptophysin, chromogranin A, CD56, keratins
Lymphoma, non-Hogkin's, usu. large cell (e.g. DLBCL) dyscohesive cells, usu. ~2x normal (resting) lymphocyte, usu. nucleolus usu. lymphadenopathy CD45, CD20, TdT, CD3

Notes:

IHC panel

Gino's panel:[6]

Lesion NB84 Myogenin Desmin CD99 CD45
Lymphoma -ve -ve -ve +ve/-ve +
Ewing sarcoma +ve/-ve -ve -ve +ve (membranous) -
Neuroblastoma +ve -ve -ve +ve/-ve -ve
Rhabdomyosarcoma -ve +ve +ve -ve -ve

See also

References

  1. URL: http://www.thedoctorsdoctor.com/diseases/small_round_blue_cell_tumor.htm. Accessed on: 2 July 2010.
  2. 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 1867426. PMID 17251339. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1867426/.
  3. PST. 14 February 2011.
  4. URL: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002168/. Accessed on: 4 April 2011.
  5. 5.0 5.1 Wippold FJ, Perry A (March 2006). "Neuropathology for the neuroradiologist: rosettes and pseudorosettes". AJNR Am J Neuroradiol 27 (3): 488–92. PMID 16551982.
  6. G. Somers. 22 March 2011.