Low power: DQ stain
Cellular smear showing small blue cells predominantly singly dispersed
Medium power: DQ stain
Small blue cells with larger light cells and smaller dark lymphocytoid cells
Note glycogen in background giving tigroid background
High power: DQ stain
Small blue cells of Ewing sarcoma
Note glycogen in background giving tigroid background
High power: DQ stain
Small blue cells with larger light cells with more open chromatin and smaller dark lymphocytoid cells with more condensed chromatin
Note glycogen in background giving tigroid background
High power: DQ stain
Ewing sarcoma cells with vascular cores with endothelial cells
High power: Pap stain
Small blue cells with larger cells with open chromatin and smaller lymphocytoid cells with condensed chromatin
High power: Pap stain
Ewing sarcoma
D/D other small blue cell tumors including lymphoma
High power: Pap stain
Small blue cells of Ewing sarcoma
High power: Pap stain
Small blue cells with light and dark cells
High power: Pap stain
Small blue cells with light and dark cells
Cell block: H&E stain
Small blue cell tumor
Cell block: H&E stain
IHC required to distinguish from other small blue cell tumors
Ewing sarcoma
Cell block: H&E stain
Ewing sarcoma small blue cells
Features
• Highly cellular
• Small blue cell tumor
• Predominantly single cells
• Small sheets and clusters
• 2 cell population: light and dark cells (more prominent on DQ)
• Indistinct cell borders
• Light cells larger histiocytic cells with open blast-like pale chromatin
• Dark cells small, lymphocytoid with condensed chromatin
• Round nuclei
• Naked nuclei may be present
• Chromatin open or condensed (see above)
• Nucleoli may be seen in the larger light cells
• Multinucleation rare
• Nuclear grooves may be present
• May have tigroid background due to cytoplasmic glycogen
• Mitosis rare
• Necrosis may be seen
• IHC: Usually expresses WT- 1, FLI- 1, c- kit, CD99, CD56, synaptophysin, cytokeratin (+/- )
• Translocation t(11;22) EWS:FLI1
Akhtar M et al. Cancer. 1985 Apr 15;55(8):1805-17.
Kontozoglou T et al. Acta Cytol. 1986 Sep-Oct;30(5):513-8.