Rhabdomyosarcoma of the liver associated with long-term oral contraceptive use. Possible role of estrogens in the genesis of embryologically distinct liver tumors.

We report a case of rhabdomyosarcoma arising in a 34-year-old woman with a 16-year history of oral contraceptive use. This is the first reported case of hepatic rhabdomyosarcoma associated with oral contraception. The tumor did not grossly or microscopically involve biliary structures or gall bladder. It was mostly comprised of undifferentiated spindle cells that were histologically similar to embryonal sarcoma. Foci of cells showing rhabdomyoblastic differentiation blended into poorly formed muscle bundles. No epithelial neoplasm was identified by either morphologic or immunohistochemical analysis. A review of the literature reveals that, although the incidence is low, mesenchymal neoplasms of the liver have been associated with oral contraceptive use. Furthermore, there is now evidence that a multipotential progenitor cell exists that can give rise to both epithelial and mesenchymal neoplasms. Thus, there may be a common precursor cell on which estrogens could act, and which could give rise to epithelial, mesenchymal, or mixed neoplasms. Finally, we suggest that embryonal sarcomas of the liver can undergo further differentiation to more well-defined mesencymal elements.