Alectinib as salvage therapy for metastatic UIMT following misdiagnosis: A case enabling definitive surgery and prolonged remission.

[BACKGROUND] Uterine inflammatory myofibroblastic tumor (UIMT) is a rare, aggressive tumor often mistaken for uterine fibroids. This case report discusses managing advanced UIMT after a misdiagnosis and assesses the effectiveness of the anaplastic lymphoma kinase (ALK) inhibitor, alectinib, as a targeted treatment.Case presentationA 29-year-old woman had a laparoscopic myomectomy for presumed uterine fibroids. Three months later, she developed abdominal distension, vaginal bleeding, and fever. Pathological evaluation confirmed a diagnosis of UIMT with aggressive behavior, and imaging showed extensive abdominal metastases. She received supportive therapies including hepatoprotection, infection control, and hemostasis. Due to the substantial tumor burden and malnutrition, targeted therapy with the ALK inhibitor alectinib was initiated, informed by ALK-p80 positivity on IHC. Her symptoms relieved significantly, and pelvic masses reduced by 53.9 % after two treatment cycles. She subsequently underwent a total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, and resection of pelvic and abdominal lesions. Post-surgery, she continued alectinib with no recurrence for over 10 months till now. Next-generation sequencing (NGS) revealed an FN1-ALK fusion and a novel MTAP-CDKN2A fusion.

[CONCLUSIONS] This case highlights the significant efficacy and safety of alectinib in the management of advanced, recurrent, and aggressive UIMT, while also emphasizing the essential role of multidisciplinary management. It provides valuable insights and serves as a reference for the management of similar rare cases.