A 74-year-old woman with history of prior hysterectomy presented with intermittent gross hematuria for four months in April 2024. She has visited several specialists including urologist and gynecologist during the past months. Initial workup at urologic clinic showed no remarkable finding in abdominal ultrasound and cystoscopy. However, pap smear indicated melanoma, and MRI was arranged in May 2024, revealing a 2.5 cm mass at introitus and possibly invades urethra, nodular lesions at posterior wall of middle vagina, posterior fornix, and metastatic left inguinal lymphadenopathy. Repeating cystoscopy in June showed a prominent mass at vagina, abutting urethra meatus with near obstruction. No metastases were noted on chest CT and bone scan. In collaboration with gynecologist, the patient underwent urethrectomy, total vaginectomy, left inguinal lymph node dissection, and permanent suprapubic cystostomy in 2024/6. The urethra, inguinal lymph node and cervix all reported malignant melanoma on pathology. The patient recovered well and was referred to oncology for adjuvant therapy. Three months post-operation, she was free of local recurrence.

Case report

Malignant melanoma (MM) is considered one of the most aggressive cancers and accounts for about 0.03% of all cancers. Primary malignant melanoma of cervix (PMMC) is extremely rare and has the worse prognosis among all melanomas. Studies suggest that patients with FIGO stage III-IV disease, lymphatic metastases, and total hysterectomy face an increased risk of death. There is little consensus on the optimal treatment strategy for PMMC and surgery remains the preferred treatment option. Of all the adjuvant treatments, chemotherapy had better overall survival than the others. Primary malignant melanoma of the urethra (PMMU) is rare as well and accounts for 0.2% of all melanomas. It occurs more in female than men and presents with hematuria, voiding difficulty and discharge. There are only several case reports discussing the recommended therapy. Though few case reports address treatment, a large case series recommended surgery as the primary intervention, but the best adjuvant therapy remains unclear. Immunotherapy has shown promise, especially since it was first FDA-approved for melanoma. Given the lack of specific symptoms and aggressive nature, early diagnosis of PMMC/PMMU is usually challenging.

In this case, the tumor grew rapidly, with a mass lesion appearing at urethra meatus within two months. Its primary origin is believed to be the vagina, which then invaded the urethra, leading to an inevitable resection of the urethra. MM has a high propensity for lymphatic and local metastases, as seen in our case. Due to the rarity of disease, the clinical characteristics and treatment strategies do not differ between PMMC and PMMU, and adjuvant therapy should be advised for patient. Our case underscored the importance of early detection of this rare condition and multidisciplinary treatment is usually warranted.