Malignant Melanoma of the Genitourinary System

Abstract

Abstract Introduction/Objective Malignant melanoma (MM) of mucosal membranes (excluding anus and head and neck) is a rare but aggressive disease with poor outcome. There is little information available on the development mechanism, risk factors, and management of this tumor, mainly due to the low number of cases. Methods/Case Report We performed a comprehensive literature review on mucosal MM (between 1970-2020). We identified 52 papers reporting 242 patients with primary genitourinary melanomas (limited to urothelium, vagina and cervix). A comprehensive review of the demographics, stage, treatment and survival was performed. Results (if a Case Study enter NA) The demographics are provided in Table 1. In 204 cases, lesions were located in the urothelium (urethra: 202, bladder: 2) followed by 34 in the vagina and 4 in uterine cervix. None of the cases had any other known primary source of MM. Molecular studies in a subset of cases revealed alterations in c-KIT, NRAS, BRAF (non-V600E and V600E), TP53 and NF1 (Table 2). Tumor stage was provided in a few (n=10) cases (stage 1=1, stage 2=1, stage 3=3 & stage 4=5). 3 patients had distant metastasis (brain, retroperitoneal and inguinal lymph nodes). Treatment data was available in 178 cases. 177 patients were managed by surgery. In addition to surgery, 10 received chemotherapy, 7 received immunotherapy and chemotherapy, 2 received chemoradiation, 1 received immunotherapy and 1 received radiotherapy. In 43 patients, the treatment regimen was not provided. The outcome was available in 178 cases (range of follow up between 3-97 months), showing 15 deaths of disease. Median survival based on available information in 28 patients was 82% (5-year survival). Table 1 legend: Demographics of genitourinary malignant melanoma cases. Table 2 legend: Frequency of molecular alterations in genitourinary malignant melanoma. Conclusion Similarities in genetic signatures of mucosal and skin MM suggest similar mechanism of development; however, unlike skin melanoma, there is less BRAF mutation and more of PI3K/AKT/mTOR pathway alterations in mucosal MM. Prolonged administration of chemotherapy (i.e., methotrexate) and immune-modulating agents (i.e., natalizumab) may be a risk factor. In light of absence of a definite adjuvant therapy, tumor stage at the time of diagnosis and proper surgical removal have central role in the prognosis and survival of patients.