Background: Endometrial cancer is the most common gynecological cancer in developed countries. Treatment-related lymphedema negatively affects the quality of life and function of patients. This study investigated the cumulative incidence and risk factors of, and utilization of health care resources for, lymphedema in patients with endometrial cancer. Methods: We conducted a nationwide, retrospective cohort study of women with endometrial cancer who underwent cancer-direct treatment using the Korean National Health Insurance Service (NHIS) database. Patients were categorized by age, region, income, and treatment modality. Cox proportional hazards regression models were used to analyze the incidence and risk factors of lymphedema. We also analyzed utilization of health care resources for lymphedema using diagnostic and treatment claim codes. Results: A total of 19,027 patients with endometrial cancer were evaluated between January 2004 and December 2017. Among them, 2493 (13.1%) developed lymphedema. Age (<40 years, adjusted odds ratio [aOR] = 1 vs. 40–59 years, aOR = 1.413; 95% confidence interval (CI) 1.203–1.66 vs. 60+ years, aOR = 1.472; 95% CI 1.239–1.748) and multimodal treatment (surgery only, aOR = 1 vs. surgery + radiation + chemotherapy, aOR = 2.571; 95% CI 2.27–2.912) are considered to be possible risk factors for lymphedema in patients with endometrial cancer (p < 0.001). The utilization of health care resources for the treatment of lymphedema has increased over the years. Conclusions: Lymphedema is a common complication affecting women with endometrial cancer and leads to an increase in national healthcare costs. Post-treatment surveillance of lymphedema, especially in high-risk groups, is needed.

Isolated pelvic nodal metastasis from carcinoma of unknown primary origin (CUP) is rare. Evaluation should prioritize gynecological and anorectal sites based on pelvic lymphatic drainage. Although spontaneous regression of these primary lesions is exceptional, regressed lesions can present as CUP, necessitating diagnostic caution. Here, we report the case of a 40-year-old woman with a solitary, intensely fluorodeoxyglucose F-18 avid left obturator lymph node and a subtle endocervical abnormality on pelvic magnetic resonance imaging. Loop electrosurgical excision revealed a Nabothian cyst only. Excisional nodal biopsy by polymerase chain reaction revealed metastatic squamous cell carcinoma with diffuse block-type p16 and human papillomavirus (HPV) 16. Considering the potential for a primary cervical tumor along the obturator drainage pathway, the patient underwent hysterectomy with pelvic lymph node dissection. No residual invasive carcinoma was found; however, HPV16 was detected in the cervix with a low-grade squamous intraepithelial lesion, supporting a regressed cervical focus. She received adjuvant cisplatin-based chemoradiotherapy and has remained disease-free for 56 months. This case highlights the diagnostic value of integrating lymphatic anatomy with the molecular profile of HPV. Cervical squamous cell carcinoma rarely regresses and presents solely as an isolated nodal disease.