Parotid melanoma of unknown primary

Purpose: Rarely, melanoma is discovered in the parotid gland without an identifiable primary site. It is not known how patients with parotid melanoma of unknown primary (PMUP) compare to those with a known primary (PMKP). As such, we describe the largest series of patients with PMUP to date and compare them to patients with PMKP. Methods: We analyzed cases from three sources: (1) the University Hospitals Case Medical Center pathology database (n = 45), (2) the Surveillance, Epidemiology, and End Results 18 database (n = 33), and (3) a comprehensive literature search (n = 32). Results: PMUP patients were predominately male and presented at a mean age of 56 years. When compared to PMKP, PMUP cases were more likely to be diagnosed in the parotid parenchyma, present with stage IV disease, and develop distant metastases during follow-up in a shorter amount of time. However, there was no difference in overall survival between patients with PMUP and PMKP presenting with stage-matched disease. Conclusions: Overall survival is similar for stage-matched patients with parotid melanoma presenting with an unknown and known primary site.