The rhabdomyoblast in mixed Müllerian tumors of the uterus and ovary. An immunohistochemical study of myoglobin in 25 cases.

Forty per cent of 25 uterine and ovarian mixed müllerian tumors contained stainable myoglobin that was present in the abundant cytoplasm of large rounded tumor cells. Intracytoplasmic cross striations identified rhabdomyoblasts in 32% of the cases, but were difficult to find. The authors believe that the immunoperoxidase technic successfully demonstrates skeletal muscle differentiation in a high proportion of mixed müllerian tumors and may be employed as a suitable diagnostic aid. However, the nonspecific staining of benign and malignant squamous elements should be interpreted with caution.