Multiple primary melanomas versus single melanoma of the head and neck: a comparison of genetic, diagnostic, and therapeutic implications.

Single primary and multiple primary melanomas (MPMs) of the head and neck region may be confused at first glance because of the common clinical and dermoscopic patterns. An inaccurate diagnosis may lead the clinician to a wrong diagnostic and therapeutic pathway because MPMs occurring in familial or sporadic settings are often involved in individual cancer susceptibility. We investigated the clinical, demographic, histological, and survival differences between MPMs and single melanoma occurring in the head and neck region. A retrospective analysis of medical and histologic records from 217 melanomas of the head and neck region was carried out. Malignant neoplasms affecting MPMs patients were also reported. Mutational analysis of specific genes was carried out when clinical data and family history were suggestive for a familial/hereditary setting. Two hundred and five out of 217 (94.5%) patients were affected by single primary melanoma and 12 (5.5%) by MPMs of the head and neck region. Individuals affected by MPMs were distinguished by a significantly higher mutation frequency and a higher prevalence of malignant neoplasms such as renal cancer. Genetic testing showed germline mutations affecting MITF E318K, CDKN2A genes. Our data highlight the importance of strict cancer surveillance in individuals with MPMs and the role of appropriate genetic counseling and testing in selected patients. Finally, personalized clinical and instrumental screening and follow-up strategies should also be based on mutational status. A heightened level of suspicion is required in the clinical management of mutation carriers.