Embryonal Rhabdomyosarcoma - Rhabdomyoblasts
Better-differentiated embryonal rhabdomyosarcomas (RMS) have abundant rhabdomyoblasts, in addition to the primitive-appearing hyperchromatic cells. Rhabdomyoblasts are large round or oval cells with abundant deeply eosinophilic cytoplasm. Several rhabdomyoblasts can be seen in this image. The cytoplasm of rhabdomyoblasts contains granular, stringy, or fibrillar eosinophilic material arranged concentrically around the nucleus. In addition, there are degenerated rhabdomyoblasts with glassy or hyaline densely eosinophilic cytoplasm and pyknotic nuclei.