Background: Abnormal uterine bleeding is a common phenomenon in perimenarchal females. Though most cases of abnormal bleeding are due to anovulatory bleeding or bleeding disorders, rare cases are attributable to underlying malignancy. Case: Here we report a 12-year-old female patient who presented with abnormal uterine bleeding three months after menarche. She was ultimately diagnosed with a pelvic sarcoma of unknown primary origin. She was subsequently treated with chemotherapy, whole pelvic radiation, and hysterectomy with bilateral salpingo-oophorectomy. Summary: Abnormal uterine bleeding unresponsive to conventional temporizing measures should be thoroughly evaluated. Management of pelvic malignancies in the pediatric population requires cooperation amongst specialists from an array of disciplines. © 2011 North American Society for Pediatric and Adolescent Gynecology.
