Case Report: Primary malignant melanoma of the uterine cervix with early recurrence following radical surgery and immunotherapy

Abstract

Background Primary malignant melanoma of the uterine cervix (PMMC) is an exceptionally rare mucosal malignancy with an aggressive clinical behavior and no established standard of care. Distinguishing a primary cervical melanoma from metastatic disease is particularly challenging and requires integration of pathological findings with comprehensive evaluation for an alternative primary site. Case presentation We report a 67-year-old postmenopausal woman presenting with vaginal bleeding and an apparently benign endocervical polyp. Histopathological and immunohistochemical examination established the diagnosis of malignant melanoma, with diffuse SOX10, melanoma cocktail, and PRAME positivity and a Ki-67 proliferation index of approximately 40–45%. Molecular testing showed no detectable BRAF mutation. Dermatological assessment and systemic imaging identified no alternative primary melanoma or evidence of distant metastatic disease at initial staging. The patient underwent radical hysterectomy with bilateral pelvic lymphadenectomy and para-aortic lymphadenectomy and omental biopsy. Pelvic lymphadenectomy included bilateral external iliac nodal dissection, with no metastatic involvement identified in the examined lymph nodes. Postoperative pembrolizumab was subsequently initiated. Despite apparently localized disease and multimodal treatment, biopsy-confirmed vaginal recurrence developed approximately two months after surgery. Restaging 18F-FDG PET/CT demonstrated metabolically active disease involving the vaginal cuff and vagina, together with findings suspicious for external iliac nodal and hepatic involvement. Palliative external-beam radiotherapy was subsequently administered for hemostatic and locoregional control. Conclusion This case highlights the aggressive and unpredictable course of PMMC, with early histologically confirmed recurrence following radical surgery and postoperative immune checkpoint inhibition. The rapid progression observed in our patient, considered alongside the heterogeneous responses to PD-1 blockade reported in the literature, underscores the therapeutic uncertainty surrounding this rare malignancy and the need for improved predictors of treatment response.