Multiple Primary Melanomas: Retrospective Review in a Tertiary Care Hospital.

Multiple primary melanomas (MPM) refer to the occurrence of more than one synchronous or metachronous melanoma in the same individual. The aim of this study was to identify the frequency of MPM and describe the clinical and histopathologic characteristics of patients with MPM. An observational single-center retrospective study was designed based on a cohort of melanoma patients followed in a tertiary care hospital. Fifty-eight (8.9%) patients developed MPM. Most patients were men (65.5%) and the median age at the time of diagnosis of the first melanoma was 71 years old. The median time of diagnosis of the second melanoma from the first melanoma was 10.9 months, and 77.6% of second melanomas were diagnosed within the first 5 years. In total, 29 (50%) and 28 (48.3%) first and second melanomas were located in the trunk, respectively. Concordance of anatomic site between primary and subsequent melanoma was found in 46.6% of the patients. Proportion of in situ melanomas was increasingly higher in subsequent melanomas (from 36.21% of first melanomas to 100% of fifth melanomas). An increasing rate of melanomas with histological regression was observed within subsequent melanomas (from 60.3% of first melanomas to 80% of third melanomas). Our results support the importance of careful long-term follow-up with total body examination in melanoma patients.