e21588 Background: Primary mucosal melanoma arising in the urinary tract is rare and poorly characterized. Methods: The records of patients with urological mucosal melanoma who presented to the department of Renal Cancer and Melanoma of Peking University Cancer Hospital between September, 2004 and April, 2019 were reviewed. Available clinicopathological and molecular characteristics were summarized, including pathological parameters, gene mutation, primary surgical intervention, systemic treatment and clinical course. The rates of local recurrence rate, loco-regional lymph node metastasis and distant metastasis were assessed. American Joint Committee on Cancer (AJCC) TNM Staging System for bladder cancer/renal pelvis and ureter cancer/urethral carcinoma (8th ed., 2017) were adopted for staging. Results: Fifty-eight patients were involved in the study with a median age of 62.5 years (range: 32-82). The anatomic sites of the primary urological mucosal melanomas were from the urethra (89.7%), bladder (6.9%), ureter (0%) and kidney (0%), and the left (4.4%) were from multiple loci. At initial diagnosis, 75.9% (n=44) were stage I/II disease, 1.7% (n=1) stage III, and 22.4% (n=13) stage IV. There was 3.4% incidence of CKIT mutation and 1.7% of BRAF mutation. After median follow-up of 22.6 mo, 31.4% (16/51) relapsed locally after organ-preserved surgery. 21.6% (11/51) and 39.2% (20/51) developed metastases to reginal lymph nodes and distance, respectively. The median relapse free survival and median overall survival were 12.2 (95%CI: 7.9-16.4) mo and 33.9 (95%CI: 19.2-48.6) mo, respectively. Univariate Cox analysis showed that TNM stage and systemic adjuvant therapy were the prognostic factors of OS, while no association was found with Breslow thickness, miotic rate, ulceration and gender. Conclusions: Urological mucosal melanoma predominantly arises from lower urinary tract with rare BRAF and CKIT mutation. AJCC TNM Staging System for urothelial carcinoma is proved practical for urothelial melanoma, which should be validated in larger population. Future research is required to identify adjuvant treatment approaches to improve disease outcomes.
Impact of the TNM staging system for thymoma
