Striated muscle heteroplasia in the uterine round ligament. A report of 30 cases.

The presence of nonneoplastic mature striated muscle, ie, striated muscle heteroplasia, is described in the proximal stumps of the round ligaments of the uterus. It was an incidental finding in 30 (2.8%) of 1064 surgical specimens studied without clinical or pathologic significance. It is deemed to represent aberrant persistence, differentiation, and maturation of gubernacular rhabdomyoblasts, which normally involute in female fetuses. The reasons for its sporadic occurrence in normal adult women are unknown.