Radical tumor resection of a relapsed high-grade endometrial stromal sarcoma with an extremely rare mutation: a case report.

Background: Endometrial stromal sarcomas (ESS) are rare uterine mesenchymal tumors that histologically resemble endometrial stroma of functioning endometrium. The key characteristic of those tumors is the difficulty to diagnose preoperatively that leads to high rate of misdiagnosis. The aim of this case report is to present an extremely rare mutation of these already rare tumors and urge for more personalized therapies in the future.

Case description: We present a case of a 62-year-old postmenopausal patient initially diagnosed with high-grade ESS (HG-ESS). In her routine follow-up, her computerized tomography (CT) and positron emission tomography-CT (PET-CT) scan showed a relapse in the vaginal vault and enlarged left iliac lymph nodes. The patient did not respond to chemotherapy and suffered from severe abdominal pain and her quality of life severely deteriorated. A cytoreduction laparotomic surgery was decided with complete resection (R0) of the tumor in the pelvis with no visible residual disease. Chemosensitivity and gene expression analysis report showed a high tumor mutation burden with 11 mutations/Mb and the detection of COL1A1-PDGFβ fusion. COL1A1-PDGFβ fusion is an extremely rare mutation observed in ESS with only a handful of cases in the literature and is suggestive of potential therapeutic benefit from imatinib administration. HG-ESS have frequent recurrences and intermediate prognosis.

Conclusions: Recurrent or advanced tumors should be treated aggressively with chemotherapy and radiation. Effort for complete resection and targeted therapy should be offered to the patients. Discovery of rare mutations might offer better personalized therapies in the future. Despite its radicality, cytoreductive surgery is a valid option in cases where life quality has severely deteriorated, offering a few qualitative months of life to the patient.