Low power: DQ stain
Cellular smear of small round blue cell tumor
Medium power: DQ stain
Poorly cohesive clusters of small round blue cell tumor
Note tigroid background
High power: DQ stain
Varying sized small blue cells with occasional binucleation and vacuolated cytoplasm
Low power: Pap stain
Cellular smear of small round blue cell tumor with alveolar pattern
Medium power: DQ stain
Cellular smear of small round blue cells, variation in nuclear size and shape, granular chromatin and occasional floret cell
Cell block: H&E stain
Features
• Highly cellular with alveolar pattern
• Poorly cohesive cells surrounded by stroma
• Solid nests/ sheets may be seen
• Small blue cells tumor
• Small round blue cells
• Floret cells: giant cells with peripheral wreath of nuclei
• Rhabdomyoblast/ strap cells (may have cytoplasmic cross-striations)
• Nuclei with variation in size and shape
• Coarse chromatin
• Prominent nucleoli
• Binucleation or multinucleation may be seen
• May have tigroid background from cytoplasmic glycogen
• IHC: Usually express Vimentin, Desmin, SMA, MyoD1, myogenin
• Translocation t(2;13) FOX01(FKHR):PAX3 or t(1;13) FOX01(FKHR):PAX7
Pohar-Marinsek Z et al. Acta Cytol. 2000 Jul-Aug;44(4):524-32.
Das K et al. Diagn Cytopathol. 2006 Oct;34(10):704-6.