Ultrastructure of a benign polypoid rhabdomyoma of the vagina

Polypold vaginal lesions containing striated muscle characteristically give rise to a diagnosis of sarcoma botryoides with its consequent therapeutic and prognostic implications. This report describes the second patient in the American literature with a benign polypoid vaginal tumor containing striated muscle. The patient was an asymptomatic 50-year-old Caucasian woman with a 2-year history of a nonulcerated polypoid mass in the anterior third of the vagina. She has remained asymptomatic and without recurrence 6 months after local excision of the lesion. Histologically, there was an edematous stroma with rhabdomyoblasts having longitudinal myofibrils and conspicuous cross striations diffusely sprinkled among mature fibroblasts and unit fibrils of collagen. There was no mitotic activity or cellular atypia. Ultrastructural study disclosed that a majority of the rhabdomyoblasts were composed of well-organized sarcomeric units with the Z bands in register, reminiscent of normal striated muscle. Our studies indicate that the vaginal rhabdomyoma has distinctive histologic and clinical features which differentiate it from other polypoid vaginal lesions as well as from rhabdo-myomas of skeletal muscle.