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]

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

Tumour Key histologic features History Key IHC /
special stains
Hepatoblastoma 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 WT-1+
Retinoblastoma eye
Medulloblastoma
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