Poor Prognosis in Low-Grade Endometrial Stromal Sarcoma With Cyclin-Dependent Kinase Inhibitor 2A Homozygous Deletion: A Case Study.

Low-grade endometrial stromal sarcoma (LGESS) typically has a favorable prognosis. Hormone therapy is considered the first choice of treatment for recurrent LGESS. In this report, we describe a case of recurrent LGESS where hormone therapy was ineffective, chemotherapy showed a partial response (PR), and pazopanib resulted in stable disease (SD). A 50-year-old patient with LGESS underwent a simple total hysterectomy and bilateral adnexectomy (pT1aN0M0, stage IA). Five years later, pelvic tumors and ascites were observed. Exploratory laparoscopy revealed bloody ascites, an 8 cm pelvic tumor, and extensive peritoneal dissemination. Nuclear atypia of the tumor cells was mild, pleomorphism and mitotic figures could not be confirmed, and necrosis was not observed. Immunostaining was positive for CD10 and estrogen receptor, negative for the BCL6 corepressor (BCOR), and showed a low Ki-67 index. Fluorescence in situ hybridization (FISH) examination of the tissue showed rearrangement of the JAZF zinc finger 1 (JAZF1) gene. Multigene panel testing revealed a homozygous deletion of cyclin-dependent kinase inhibitor 2A (CDKN2A). Accordingly, the patient was diagnosed with recurrent LGESS and was treated with an aromatase inhibitor, followed by medroxyprogesterone acetate; both were ineffective. The patient had a PR to chemotherapy (doxorubicin/ifosfamide) and SD to pazopanib. The patient died 1.5 years after recurrence. In conclusion, we present a case of LGESS with a poor prognosis where hormone therapy was ineffective, and chemotherapy and pazopanib were both partially effective. The poor prognosis may have been associated with the CDKN2A homozygous deletion.