Small round cell tumours

• neuroblastoma

• rhabdomyosarcoma

• PNET / Ewing's sarcoma

• mesenchymal chondrosarcoma

• lymphoma / leukaemia: CD45 positivity is very specific. May also be vimentin positive. Lymphoblastic lymphoma may be positive for CD99.

• intra-abdominal desmoplastic small round cell tumour and other polyphenotypic small round cell tumours

• rhabdoid tumour

• small cell carcinoma

• small cell angiosarcoma

• small cell variant of synovial sarcoma

• small cell melanoma: these tumours appear to be routinely positive for S-100 and Melan-A, with variable positivity for HMB-45¹

Immunohistochemistry (this table is at an early stage of construction):

	rhabdomyosarcoma	neuroblastoma	PNET / Ewing's sarcoma	mesenchymal chondrosarcoma	polyphenotypic small round cell tumour / intra-abdominal desmoplastic small round cell tumour
vimentin	always positive		more often positive in ES than in PNET		97%	vimentin
desmin	almost always positive	negative	negative	negative	90%	desmin
muscle-specific actin	usually positive		negative	negative	usually negative	muscle-specific actin
Myo-D1	82%-100% of cases	may be positive	may be positive			Myo-D1
myogenin	usually positive		negative		usually negative	myogenin
myoglobin	usually positive		negative			myoglobin
NSE			most cases positive	most cases	81%	NSE
CD57			most cases positive	positive		CD57
neurofilament			most cases positive			neurofilament
CD99			positive	most cases positive	some cases	CD99
chromogranin			negative		usually negative	chromogranin
synaptophysin				negative		synaptophysin
GFAP			negative	some CNS cases may be positive		GFAP
cytokeratin			up to 20% of cases (27/1043)	some CNS cases may be positive	86%	cytokeratin
EMA				negative	93%	EMA
Factor VIIIRA			negative			Factor VIIIRA
Factor XIIIA				positive		Factor XIIIA
S-100				only chondroblastic islands are positive		S-100
	embryonal rhabdomyosarcoma	neuroblastoma	PNET / Ewing's sarcoma	mesenchymal chondrosarcoma	polyphenotypic small round cell tumour / intra-abdominal desmoplastic small round cell tumour

References

Diagnostic Immunohistochemistry edited by Professor D. J. Dabbs, pages 78-84.

Blessing K, Grant JJh, Sanders DSA et al. Small cell malignant melanoma: a variant of naevoid melanoma. Clinicopathological features and histological differential diagnosis. J Clin Pathol 2000; 53:591-5.

³Chu, P. G. and L. M. Weiss (2002). "Keratin expression in human tissues and neoplasms." Histopathology 40(5): 403-39. (Summary data from multiple papers)

This page last revised 4.1.2004.

©SMUHT/PW Bishop