Orbital rhabdomyosarcoma. Immunohistochemical studies of seven cases.

An immunohistochemical analysis using a series of mono- and polyclonal antibodies against myoglobin, desmin, vimentin, actin, NSE, S-100 protein and keratin was done on alveolar rhabdomyosarcoma (3 cases), embryonal (3) and pleomorphic rhabdomyosarcoma of the orbit (1). All tumors were stained by monoclonal antibodies to desmin and vimentin, whereas 6 of the 7 cases were stained by myoglobin. The results indicate that desmin and vimentin are highly sensitive immunohistochemical markers for the diagnosis of rhabdomyosarcoma, especially in poorly differentiated ones.