Multiple Primary Melanomas Occurring Around the Same Time: A Review of Terminology and Implications

As the incidence of melanoma and resulting death rate continue to rise, it has become increasingly important to recognize clinical signs of melanoma to ensure early intervention. The classic signs of ABCDE refer to asymmetry, irregular borders, color variegation, diameter/ugly duckling, and evolution of the lesion over time. Melanoma patients are at a significantly higher risk of having subsequent primary melanomas. In fact, the relative risk of developing a melanoma after a previous melanoma was 12- to 26-fold compared to the general population, according to a large European population-based study of 57465 melanoma patients.¹ Multiple primary melanomas (MPMs) have been reported to occur in 2-10% of melanoma patients.^2-6 Patients with MPMs are more likely to be older, have superficial spreading melanomas, have negative sentinel lymph nodes, and lack lymphovascular invasion with the initial tumor.⁷ Occasionally, some of these patients may be diagnosed with MPMs at or around the same time, as reported in case reports and population-based studies. Adjectives used to describe the close temporal proximity among diagnosed melanomas include “synchronous”, “concurrent”, and “simultaneous”. However, the usage of these terms varies in the literature. Our objective is to review the literature to elucidate the definitions of these commonly used temporal adjectives and determine the reported incidence of MPMs diagnosed at or around the same time, with a focus on cutaneous melanoma.

Reviewing the Various Terminology Used
Different temporal adjectives that have been used to describe close temporal proximity among diagnosed melanomas include “concurrent”, “simultaneous”, and “synchronous” (Table 1). To avoid any confusion, we will use the phrase “around the same time” in this section to replace usage of temporal adjectives listed above. Johnson et al. defined “concurrent” as within 1 month of the initial diagnosis of the index primary melanoma.4 Moseley et al. defined “synchronous” as within 3 months of initial evaluation.⁵ Titus-Ernstoff et al. appeared to use the term “synchronous” as a synonym of “simultaneous”.⁸ Krajewski et al. defined “synchronous” as within 6 months of diagnosis of the index primary melanoma.² Kang et al. used the terms “concurrent” and “synchronous” interchangeably, likely describing melanomas that were diagnosed at the same time.³ Gupta et al. defined the term “synchronous” as a time interval of 0 month between initial and subsequent diagnoses.⁹ Brobeil et al. defined the term “synchronous” as within two months of the first melanoma diagnosis.10 Savoia et al. defined the term “synchronous” as within 30 days of excision of the first melanoma.¹¹ The term “simultaneous” has been used in multiple case reports, describing cases of melanoma patients with more than one primary melanomas that were diagnosed at the same time.^12-15 The term “synchronous” has been used in case reports to describe MPMs being diagnosed at the same and 3 months after the first melanoma.^16-18 For unstated reasons, different au-