UESLs are usually diffusely positive for vimentin and a1-antitrypsin and focally positive for cytokeratin, desmin, α-SMA, muscle-specific actin, CD68, myoglobin, neuron-specific enolase, S100, and CD34, suggesting that an embryonal sarcoma is undifferentiated [13]. The gene discussed is ACTA1; the disease is undifferentiated (embryonal) sarcoma.