Atypical cutaneous melanocytic tumours arising in two patients with Li-Fraumeni syndrome

Melanoma in patients with Li-Fraumeni syndrome (Review)

Li-Fraumeni syndrome (LFS) is a cancer-prone, autosomal dominant syndrome caused by underlying germline gene mutations of TP53, a tumor-suppressor gene encoding the p53 protein with a major role in apoptosis, DNA repair and cell cycle regulation. Cumulative cancer incidence for LFS patients by the age of 70 years is 80-100%, mostly involving adrenocortical carcinoma, brain tumors, bone and soft tissue sarcomas, leukemia and female breast cancer from the age of 20 years. Dominant negative TP53 variant is correlated with an increased tumorigenesis risk in LFS. Sporadic TP53 mutations are related to almost half of global cancers since p53 in addition to p73 protein represent essential players in anticancer cellular protection. Epidemiological aspects concerning skin cancers, especially malignant melanoma (MM), in LFS are less clear. A low level of statistical evidence demonstrates LFS cases with pediatric MM, multiple MM, spitzoid MM, atypical presentations, mucosal and uveal MM. Retrospective cohorts indicate a higher cumulative risk than the general population by the age of 70 years for MM and basal cell carcinoma. Non-syndromic and syndromic TP53 mutations are a major pathway of metastasis, including MM. In LHS, an important level of awareness involves skin cancers despite not being a part of the typical malignancy-containing picture. Additional data are crucially needed. However, at least one dermatologic control is a step in the multidisciplinary panel of surveillance of these patients; but in cases with benign and pre-malign pigmentations, serial dermatoscopy and full body photography are recommended for early melanoma detection in order to improve the prognosis and to reduce the overall malignancy burden.

Cutaneous Melanomas Arising during Childhood: An Overview of the Main Entities

Cutaneous melanomas are exceptional in children and represent a variety of clinical situations, each with a different prognosis. In congenital nevi, the risk of transformation is correlated with the size of the nevus. The most frequent type is lateral transformation, extremely rare before puberty, reminiscent of a superficial spreading melanoma (SSM) ex-nevus. Deep nodular transformation is much rarer, can occur before puberty, and must be distinguished from benign proliferative nodules. Superficial spreading melanoma can also arise within small nevi, which were not visible at birth, usually after puberty, and can reveal a cancer predisposition syndrome (CDKN2A or CDK4 germline mutations). Prognosis is correlated with classical histoprognostic features (mainly Breslow thickness). Spitz tumors are frequent in adolescents and encompass benign (Spitz nevus), intermediate (atypical Spitz tumor), and malignant forms (malignant Spitz tumor). The whole spectrum is characterized by specific morphology with spindled and epithelioid cells, genetic features, and an overall favorable outcome even if a regional lymph node is involved. Nevoid melanomas are rare and difficult to diagnose clinically and histologically. They can arise in late adolescence. Their prognosis is currently not very well ascertained. A small group of melanomas remains unclassified after histological and molecular assessment.

Targeted germline sequencing of patients with three or more primary melanomas reveals high rate of pathogenic variants

Individuals with multiple primary melanomas have rates of germline CDKN2A pathogenic variants of 3%-18%, and are also frequent carriers of variants in the melanocortin-1 receptor. Few patients with numerous (≥3) primary melanomas have been studied with respect to these or other potential germline pathogenic variants. We investigated 46 patients with ≥3 primary melanomas (3, n = 17; 4, n = 14; 5-14, n = 15) to determine if higher rates of germline pathogenic variants of CDKN2A, MC1R, or other cancer genes could explain their extreme melanoma phenotype. Most (43/46, 93%) patients had variants in MC1R and 11/46 (24%) had CDKN2A pathogenic variants, but only male sex and having two variants in MC1R correlated with increasing number of melanomas. Panel screening of 56 other cancer predisposition genes did not reveal other germline pathogenic variants associated with melanoma (CDK4, BAP1, POT1), although pathogenic variants in TP53, CHEK2, and BRCA2 were present in three separate patients and some patients had variants of uncertain significance. In summary, targeted germline sequencing of patients with ≥3 primary melanomas revealed a high rate of pathogenic variants in CDKN2A and other known cancer genes. Although further investigation of these pathogenic variants and variants of uncertain significance is needed, these results support cancer gene panel testing in individuals diagnosed with ≥3 melanomas.