Metastatic High-Grade Endometrial Stromal Sarcoma Presenting With Recurrent Bilateral Pneumothoraces

Endometrial stromal sarcoma is a rare malignancy that can be difficult to diagnose due to its nonspecific presentation. Unfortunately, the presenting symptoms of abnormal uterine bleeding (AUB), anemia, and pelvic pain overlap with symptoms of benign uterine fibroids, which can delay diagnosis. Additionally, initial evaluations with imaging or even a negative endometrial biopsy may provide false reassurance. Due to novelty, mimicry of benign uterine processes, and high false-negative endometrial biopsy rates, this malignancy is often diagnosed at advanced stages. In this case vignette, we describe a case of metastatic high-grade endometrial stromal sarcoma (HG-ESS) presenting with menorrhagia, pulmonary embolism, and recurrent pneumothoraces in a 42-year-old G1P1 woman.