Synchronizing the Nomenclature Surrounding Synchronous Primary Cutaneous Melanomas: A Systematic Review.

Objective: There is little consensus regarding the nomenclature and prognostic implications of synchronous melanomas. Here, we present a case of synchronous cutaneous melanoma and perform a systematic review of similar cases in the literature.

Methods: Pubmed and EMBASE databases were queried for relevant English-language articles published from inception until 2023. Cases of "multiple primary cutaneous melanomas" that occurred within a time frame of three months or less were included. Exclusion criteria included non-cutaneous melanomas and cases without specific time intervals or those occurring beyond a three-month period. Data including patient age, sex, risk factors, cutaneous melanoma (CM) anatomic location, CM clinicohistologic features, and prognosis were extracted from relevant articles.

Results: Nineteen case reports/series documenting 22 patients with multiple primary melanomas (MPM) occurring within a three-month interval. Overall, 66 melanomas were diagnosed, with an average of three (SD±2.1, median: 2) per patient. A majority (63%) of patients had one or more risk factors for skin cancer. Subsequent CM found within three-month interval were thinner than the first found (index) CM, more likely to be melanoma in situ (MMis) and have highest degree of anatomic concordance if the index lesion was first found on the trunk (50%). Two retrospective cohort studies (n=4,703; n=13) of melanomas occurring within three-month interval found similar results.

Limitations: Limitations to our review included inconsistent reporting in the literature and use of terminology and a limited number of case reports and case series found in the literature.

Conclusion: Synchronous primary cutaneous melanomas are a heterogenous collection of terminologies that may limit the ability of dermatologists to accurately diagnose, prognosticate, and treat high-risk patients. Given lack of guidelines, we recommend the use of the term "synchronous" to delineate additional primary cutaneous melanomas found within a three-month interval.