Small round cell tumours

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Micrograph showing a small round cell tumour (Ewing sarcoma) in the lung. H&E stain.

Small round cell tumours (SRCT), also small round blue cell tumours (SRBCT), are a group of tumours that have a similar histologic appearance.


  • Group of tumours that is typically seen in childhood and younger adults.
  • Most common small round cell tumour is non-Hodgkin lymphoma.[1]

A short differential diagnosis of small round cell tumours

A short DDx of SRCTs:[2][3]


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).

A long differential diagnosis of small blue cell tumours

Adapted from Miller with modifications:[4]

Tumour Group Notes/comments
Malignant melanoma, small cell melanoma
PEComa mesenchymal lesion
Carcinoma not otherwise specified carcinoma
Small cell carcinoma carcinoma
Merkel cell carcinoma carcinoma
Islet cell tumour (carcinoid) carcinoma
Medullary thyroid carcinoma carcinoma
Desmoplastic small round cell tumour sarcoma
Polyphenotypic small cell tumour other
Papillary-cystic tumour of pancreas other
Pancreatoblastoma other
Acinar cell carcinoma carcinoma
Adenoid cystic carcinoma carcinoma
Cutaneous adnexal tumours (spiradenoma, acrospiroma) other
Wilms tumour other
Thymoma epithelial lesion
Metanephric adenoma of urinary tract epithelial lesion
Basaloid carcinoma / Basal cell carcinoma carcinoma
Small cell mesothelioma carcinoma [5]
Pulmonary blastoma other
Cutaneous myoepithelioma epithelial lesion [6]
Ewing sarcoma / PNET neural tumours
Neuroblastoma / esthesioneuroblastoma neural tumours
Sclerosing perineurioma neural tumours
Schwannoma neural tumours
Meningioma neural tumours
Medulloblastoma neural tumours
Central neurocytoma neural tumours
Medulloepithelioma neural tumours
Retinoblastoma neural tumours
Oligodendroglioma neural tumours
Pineocytoma neural tumours
Hemangioblastoma neural tumours may be seen extraneural
Neurogenic sarcoma neural tumours
Lymphoma lymphoid
Extramedullary leukemia lymphoid
Plasma cell myeloma lymphoid
Mastocytosis lymphoid
Plasmacytoid dendritic cell tumour lymphoid CD4 +ve, CD56 +ve[7]
Granuloma annulare histiocytic lesion
Seminoma germ cell tumour degenerative cases
Granulosa cell tumour sex cord tumour
Gynandroblastoma sex cord tumour Sertoli cell & granulosa cell
Sertoli-Leydig tumour sex cord tumour
Endometrial stromal sarcoma sarcoma may be extragenital
Adenosarcoma sarcoma glandular component may not be sampled
Rhabdomyosarcoma muscle
Skeletal muscle regeneration muscle mimics rhabdomyosarcoma[8]
Small cell leiomyosarcoma sarcoma
Small cell osteosarcoma chondro-osseous tumours
Mesenchymal chondrosarcoma chondro-osseous tumours
Myxoid chondrosarcoma chondro-osseous tumours
Proliferative myositis muscle
Fetal or genital rhabdomyoma other
Glomus tumour other
Glomangiopericytoma other
Synovial sarcoma sarcoma
Hemangiopericytoma soft tissue lesions
Small cell angiosarcoma vascular lesions
Epithelioid hemangioendothelioma vascular lesions
Solitary fibrous tumour soft tissue lesions can be myxoid
Myofibroblastoma soft tissue lesions
Angiomyofibroblastoma soft tissue lesions


  1. This DDx includes small cells that may be spindled.
  2. The DDx for large (non-pleomorphic) epithelioid cells is found in large epithelioid tumours.



  • 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:[9]

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+, S-100-
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[10]) WT-1+
Retinoblastoma Flexner-Wintersteiner rosette (rosette with empty centre (donut hole))[11] eye lesion; +/-RB1 gene mutations (familial)
Medulloblastoma Homer-Wright rosettes (rosette with a meshwork of fibers (neuropil) at the centre)[11] +/-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


IHC panel

Gino's panel:[12]

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

More general panel:[1]

  • CD45, CD20, CD3, CD99, desmin, EMA, pankeratin, synaptophysin, chromogranin, GFAP.

See also


  1. 1.0 1.1 D'cruze, L.; Dutta, R.; Rao, S.; R, A.; Varadarajan, S.; Kuruvilla, S. (Jul 2013). "The role of immunohistochemistry in the analysis of the spectrum of small round cell tumours at a tertiary care centre.". J Clin Diagn Res 7 (7): 1377-82. doi:10.7860/JCDR/2013/5127.3132. PMID 23998069.
  2. URL: Accessed on: 2 July 2010.
  3. 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.
  4. Miller RT. (Sep 2013). Atlantic Diagnostic Immunohistochemistry Symposium. St. John's, NL, Canada.
  5. Mayall, FG.; Gibbs, AR. (Jan 1992). "The histology and immunohistochemistry of small cell mesothelioma.". Histopathology 20 (1): 47-51. PMID 1310669.
  6. Kutzner, H.; Mentzel, T.; Kaddu, S.; Soares, LM.; Sangueza, OP.; Requena, L. (Mar 2001). "Cutaneous myoepithelioma: an under-recognized cutaneous neoplasm composed of myoepithelial cells.". Am J Surg Pathol 25 (3): 348-55. PMID 11224605.
  7. Reichard, KK.; Burks, EJ.; Foucar, MK.; Wilson, CS.; Viswanatha, DS.; Hozier, JC.; Larson, RS. (Oct 2005). "CD4(+) CD56(+) lineage-negative malignancies are rare tumors of plasmacytoid dendritic cells.". Am J Surg Pathol 29 (10): 1274-83. PMID 16160468.
  8. Guillou, L.; Coquet, M.; Chaubert, P.; Coindre, JM. (Aug 1998). "Skeletal muscle regeneration mimicking rhabdomyosarcoma: a potential diagnostic pitfall.". Histopathology 33 (2): 136-44. PMID 9762546.
  9. PST. 14 February 2011.
  10. URL: Accessed on: 4 April 2011.
  11. 11.0 11.1 Wippold FJ, Perry A (March 2006). "Neuropathology for the neuroradiologist: rosettes and pseudorosettes". AJNR Am J Neuroradiol 27 (3): 488–92. PMID 16551982.
  12. G. Somers. 22 March 2011.