Primary Vaginal Melanoma or Clear Cell Sarcoma: A Difficult Differential Diagnosis

Lower genital tract lesions are a frequent reason for gynecological consultation, and primary vaginal melanoma is an uncommon but aggressive form of malignancy. It primarily strikes in postmenopausal women and is often detected at an advanced stage, accounting for its poor prognosis. A 47-year-old Caucasian female patient was referred to our institution due to abnormal vaginal bleeding and a palpable lesion near the urethra, and subsequently, we present a case of primary vaginal melanoma. Histopathological and immunohistochemical studies confirmed the diagnosis of melanoma and differentiated it from clear cell sarcoma. Imaging showed multiple lung metastases, and the patient was restaged as stage IV vaginal melanoma. The patient was treated with anti-PD-1 agent nivolumab and anti-CTLA-4 agent ipilimumab, and after that, she showed a good clinical response. This case illustrates some of the difficulties in wade through the diagnosis and treatment of vaginal melanoma, as well as a powerful argument for obtaining early definitive biopsy and diagnosis. We discuss the treatment options, including surgical excision, radiation therapy, and immunotherapy, emphasizing the poor prognosis and low survival rates among patients diagnosed with an advanced stage.