Pure alveolar rhabdomyosarcoma of the corpus uteri: description of a case with increased serum level of CA-125.

We report a morphological and immunohistochemical study of a case of pure alveolar rhabdomyosarcoma of the uterus in an 80-year-old woman. The diagnostic clues were the characteristic 'alveolar' pattern of growth, the evidence of cross-striations in strap or elongated cells with abundant eosinophilic cytoplasms, the presence of multinucleated cells with peripherally placed 'wreathlike' nuclei, and the expression of muscular antigens by the tumor cells. A thorough sampling of the tumor excluded areas of other types of heterologous or homologous sarcomas or the presence of coexisting adenoma or carcinoma. The other immunohistochemical data showed a high proliferative rate as well as a high rate of p53 overexpression in the small poorly differentiated rhabdomyoblasts. Interestingly, the large differentiated rhabdomyoblasts expressed CA-125, the antigenic determinant of nonmucinous epithelial ovarian tumors. The clinical course was very aggressive: the patient died 5 months after surgery because of disease progression. The pertinent literature is discussed.