P053 Synchronous melanoma: a single-centre 5-year retrospective study

• Published in: British journal of dermatology (1951) Vol. 191; no. Supplement_1; p. i39
• Main Authors: Yong, Ji Fung, O’Connell, Michael, Durack, Alana, Paul, Lyndsey
• Format: Journal Article
• Language: English
• Published: 28-06-2024
• ISSN: 0007-0963; 1365-2133
• DOI: 10.1093/bjd/ljae090.080

Synchronous melanoma (SM) is defined as at least two melanomas diagnosed at the same time, or a second within 3 months of diagnosing the first melanoma. Previous studies have shown that 0.5% of all patients with cutaneous melanoma have synchronous second primaries. A retrospective study of melanoma data in one of the eight designated cancer centres in the Republic of Ireland was undertaken. We reviewed the demographics, risk factors and melanoma types in all the cases of SM discussed at the melanoma multidisciplinary team (MDT) meeting for the last 5 years. Melanoma MDT lists, and histopathology and clinical records were reviewed from July 2018 to July 2023 inclusive, for SMs. This study included invasive malignant melanoma (MM), lentigo maligna (LM) and melanoma in situ (MIS). In total, 1082 patients were diagnosed with cutaneous melanomas over the 5-year period. Of these patients, 42 (3.9%) with SMs were identified (26 male, 16 female). Ages ranged from 44 to 93 years. Thirty patients (71%) had SMs diagnosed at the same time, with the rest diagnosed within a 3-month period. Nine cases (21%) had a previous history of melanoma, with four having previous SMs. Other risk factors noted included history of immunosuppression (10%, n = 4), first-degree relatives with a history of melanoma (7%, n = 3) and history of previous nonmelanoma skin cancer (5%, n = 2). Of the 42 patients, four (10%) had more than two individual melanomas identified on the same occasion (three patients had three melanomas and one had five). Of these four patients, two had a first-degree family history of cutaneous melanomas and were referred for genetic testing, with results pending. Of the total number of SMs (n = 91), 29% (26) were invasive MM, 24% (22) were LM and 47% (43) were MIS. Most lesions (33%, n = 30) were located on the trunk, with 19 (58%) on the back. Twenty patients (48%) had synchronous in situ lesions (LM/MIS), 20 (48%) had LM/MIS with an invasive melanoma (pathological stage 1A to 4B) and two (5%) had synchronous stage 1a and 1b melanomas. In total, 93% of cases (n = 39) attended dermatology services for follow-up. To the best of our knowledge, this is the largest reported case series to date of SM. A higher incidence of SMs in our cancer centre is noted compared with the literature (3.8% vs. 0.5%). It highlights the importance of a full skin check, especially once a melanoma has been identified, to ensure further melanomas are not missed. For patients diagnosed with SMs, who also have first-degree family history of cutaneous melanoma, genetic testing should be considered to look for germline mutations and genetic variants.