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Alveolar and poorly differentiated rhabdomyosarcoma

1988; Wiley; Volume: 96; Issue: 7-12 Linguagem: Inglês

10.1111/j.1699-0463.1988.tb00950.x

1600-0463

Tomas Seidal, Lars‐Gunnar Kindblom, Lennart Angervall,

Lymphoma Diagnosis and Treatment

Eighteen poorly differentiated, small and dark cell malignancies afflicting young individuals without light‐microscopic evidence of a rhabdomyoblastic differentiation or a growth pattern characteristic of rhabdomyosarcoma were analyzed and compared with a series of 30 alveolar rhabdomyosarcomas of varying differentiation, where the diagnosis could be established light‐microscopically. The study comprised clinical data, light and electron microscopy and immunohistochemistry, using a battery of mono‐ and polyclonal antibodies against intermediate filaments, myoglobin, epithelial membrane antigen, neuron‐specific enolase, S‐100 and leucocyte common antigen. All 30 alveolar rhabdomyosarcomas were positive for desmin, while a minority were positive for myoglobin, using monoclonal antibodies. In 8 of the 18 small and dark cell malignancies, support for a rhabdomyoblastic differentiation was obtained by a positive staining for desmin. In only 3 of these 8 cases was there ultrastructural evidence of rhabdomyosarcoma. The results of the investigation indicate that immunohistochemistry is a more useful tool than electron microscopy in the diagnosis of poorly differentiated rhabdomyosarcoma and that the criteria for the diagnosis of poorly differentiated rhabdomyosarcoma may need to be reformulated.