Clinical histopathological features and CDKN2A/CDK4/MITF mutational status of patients with multiple primary melanomas from Bologna: Italy is a fascinating but complex mosaic

The incidence of cutaneous melanoma (cM) has increased in the last decades. Germline mutations in the high-penetrance melanoma susceptibility gene CDKN2A (Cyclin-dependent kinase inhibitor 2A) are associated with a younger age at diagnosis and an increased risk to develop pancreatic cancer.We retrospectively analyzed the data of patients with prior diagnosis of cM referring to our service from January 2005 to May 2017. The aim was to investigate the rate of multiple cMs (MPM), assessing their clinical/pathological features. Moreover, the genetic tests of patients who had undergone CDKN2A/CDKN2B, CDK4 and MITF screening were evaluated.One hundred fifteen patients (9.26%) were diagnosed with MPMs: 70 males (60.87%) and 45 women (39.13%). 75 patients (43 males and 32 females) underwent genetic screening for germline mutations. The screening revealed that 4/75 patients (5.33%) were carriers of the non-synonymous missense variation c.442G>A (p.Ala148Thr) in CDKN2A exon 2 in heterozygosis, 3 of whom had at least one in-situ melanoma. In 1 patient (1.33%) we detected the variation c.249C>A, p.His83Gln in CDKN2A exon 2 in heterozygosis and in 1 patient (1.33%) the mutation c.952G>A (p.Glu318Lys) in MITF gene was found.This study confirms the need for a full body skin examination and a prolonged surveillance in patients affected by cM, as MPMs were detected in up to 10% of total cases in our series and synchronous lesions in 1/5. Moreover, it reflects the great variability of cM high-susceptibility genes mutational status within the Italian territory. Patients carrying c.952G>A (p.Glu318Lys) MITF mutation have a higher risk to develop a nodular cM.