Recurrent Fallopian Tube Carcinosarcoma, Clinical Insights into a Rare and Lethal Gynecologic Tumor: A Case Report and Review of Therapeutic Challenges

Background: Primary fallopian tube malignant mixed Müllerian tumors (MMMTs), or carcinosarcomas, are exceptionally rare (<0.5% of gynecologic malignancies) and highly aggressive biphasic neoplasms. Their nonspecific presentation often mimics ovarian cancer, posing significant diagnostic challenges and typically conferring a poor prognosis. This report details an exceptional case of recurrent mixed papillary carcinosarcoma originating in the fallopian tube, which presented as a bilateral inguinal relapse five years after the patient achieved remission. This prolonged remission followed by such a late and unusual pattern of recurrence, particularly in the inguinal region, makes this case particularly unique and clinically insightful. Case Report: A 68-year-old female presented in 2019 with abdominal pain and ascites. Imaging and elevated CA-125 suggested ovarian cancer, but exploratory laparotomy revealed a FIGO stage IIIC primary fallopian tube carcinosarcoma with extensive local invasion, necessitating initial palliative R2 cytoreduction. Histopathology confirmed a biphasic tumor with high-grade serous carcinoma (PAX8+, WT1+, p53 null) and heterologous chondrosarcomatous components (vimentin+, H3K27me3 loss). Following 6 cycles of carboplatin/paclitaxel, a second-look surgery achieved complete R0 resection of residual sarcomatoid peritoneal deposits, followed by 3 consolidation chemotherapy cycles. Remarkably, the patient remained disease-free for 5 years. In 2024, she presented with bilateral inguinal masses. This late recurrence, particularly in the inguinal region, brought with it significant physical discomfort and, crucially, a profound psychological burden, impacting her previously stable quality of life. The patient underwent bilateral therapeutic inguinal lymphadenectomy. This intervention, while serving for palliative tumor debulking, was primarily aimed at alleviating the distressing symptoms and improving her overall quality of life, which had been severely deteriorated by the physical and psychological impacts of the relapse. Palliative lymphadenectomy confirmed late recurrence of carcinosarcoma (pure carcinoma in nodes, mixed in ulcerated mass). BRCA1 analysis is pending; she is currently receiving carboplatin/paclitaxel/bevacizumab. Discussion: This case highlights the extreme rarity of tubal carcinosarcoma and exceptional 5-year survival despite advanced stage (IIIC) and unfavorable heterologous histology. Prolonged survival likely resulted from achieving R0 resection and initial chemosensitivity. The recurrence after 5 years underscores the potential for very late relapse, necessitating long-term surveillance. Clonal evolution in the recurrence was noted. A dedicated QoL analysis emphasizes the physical, emotional, and social burdens of prolonged treatment and recurrence, advocating for integrated palliative care and patient-centered follow-up. Conclusion: Primary fallopian tube carcinosarcoma is rare and aggressive. This case shows prolonged survival is possible with aggressive multimodal treatment (optimal R0 cytoreduction, platinum-based chemotherapy), even with adverse factors. However, the risk of very late recurrence mandates indefinite follow-up. Molecular profiling may aid prognostication and targeted therapy selection. Equally critical are the profound quality of life implications of this disease and its treatment. Our patient faced cumulative physical burdens, including chemotherapy-induced neuropathy, surgical complications, and functional limitations from inguinal lymphadenectomy, alongside the psychological toll of prolonged surveillance and disease recurrence. These challenges underscore the need for early and ongoing integration of supportive care measures—such as pain management, physical therapy, and psychosocial support—into treatment paradigms. This dual emphasis on oncologic control and quality of life aligns with modern patient-centered care models and is particularly relevant for aggressive malignancies where treatment intensity must be balanced against survivorship considerations.