Embryonal Rhabdomyosarcoma : Microscopic
Microscopic Features of Embryonal Rhabdomyosarcoma (RMS): At low power, embryonal RMS shows densely packed hypercellular zones alternating with hypocellular myxoid areas (seen in this image). Depending upon the degree of differentiation, there is an admixture of small, undifferentiated, hyperchromatic round or spindle cells and differentiated eosinophilic cells (rhabdomyoblasts). Cross striations are seen in about 50% to 60% of cases. The background stroma is mostly myxoid with scant amounts of collagen.