Melanoma and melanocytic nevi in pediatric patients: a single institution experience

Melanoma in children: A systematic review and individual patient meta-analysis

The current evidence on paediatric melanoma is heterogeneous, especially regarding the prognosis of different histological subtypes. We sought to systematically review the evidence on paediatric melanoma, highlighting the major sources of heterogeneity and focusing on available data on single patients. A systematic search was performed from 1948 to 25 January 2021. Only studies reporting at least one case of cutaneous melanoma in patients aged ≤18 years were included. Unknown primary and uncertain malignant melanomas were excluded. Three couples of authors independently performed title/abstract screening and two different authors reviewed all the relevant full texts. The selected articles were manually cross-checked for overlapping data for qualitative synthesis. Subsequently data on single patients were extracted to perform a patient-level meta-analysis. PROSPERO registration number: CRD42021233248. The main outcomes were melanoma-specific survival (MSS) and progression-free survival (PFS) outcomes. Separate analyses were done of cases with complete information on histologic subtype, focusing on superficial spreading (SSM), nodular (NM) and spitzoid melanomas, as well as of those classified as de-novo (DNM) and acquired or congenital nevus-associated melanomas (NAM). The qualitative synthesis covered 266 studies; however, data on single patients were available from 213 studies including 1002 patients. Among histologic subtypes, NM had a lower MSS than both SSM and spitzoid melanoma, and a lower PFS than SSM. Spitzoid melanoma had a significantly higher progression risk than SSM and trended toward lower mortality. Focusing on nevus-associated status, DNM demonstrated better MSS after progression than congenital NAM, and no differences were highlighted in PFS. Our findings describe the existence of different biological patterns in paediatric melanoma. Specifically, spitzoid melanomas demonstrated intermediate behaviour between SSM and NM and showed a high risk of nodal progression but low mortality. This raises the question of whether spitzoid lesions are being over-diagnosed as melanoma in childhood.

Establishment and characterization of an immortalized human giant congenital melanocytic nevi cell line

Treatments for giant congenital melanocytic nevi (GCMN) are extremely limited. Thus, there is an urgent need for development of relevant targeted therapies. However, current lack of preclinical cell models restricts progress in GCMN research. In this study, we aimed to establish and characterize an immortalized GCMN cell line. GCMN cells were successfully immortalized by means of lentivirus-mediated simian virus 40 large T transfection. The immortalized GNC cell line (ImGNC) showed lower proliferation rate and higher melanin content than primary melanocytes. Expression levels of the differentiation gene MITF and stemness genes TWIST1, SNAI1, and FOXD3 were elevated in ImGNCs; however, the established ImGNC cell line was immortalized but not transformed. Sanger sequencing detected the heterozygous NRAS^Q61K mutation in ImGNCs, but not the BRAF^V600E mutation. Despite carrying the NRAS^Q61K allele, ImGNCs demonstrated suppressed MAPK activation and elevated PI3K/Akt activation, as compared with primary melanocytes. Drug sensitivity analysis showed that ImGNCs are more sensitive to PI3K/Akt and Bcl-2 inhibitors than to MEK or ERK inhibitors. Unlike the proliferation-inhibiting effect of PI3K/Akt inhibitors, the Bcl-2 inhibitor navitoclax promptly promoted apoptosis in ImGNCs. Considering the low proliferation characteristics of GCMN in vivo, Bcl-2 may be a potential therapeutic target that warrants further research.

Giant congenital nodular melanoma in a newborn: a case report and literature review

BACKGROUND

Malignant melanoma (MM) arises predominantly after adolescence and is uncommon in children. Congenital MM in newborns is even rarer with a dearth of published literature; as a consequence, there is no uniform standard for the pathogenesis and treatment for neonatal malignant melanoma. Herein we report a case of giant congenital nodular MM in a newborn, including its clinical, imaging, pathological and molecular pathological features. This case is the largest giant congenital primary nodular malignant melanoma in utero in neonates currently reported in China.

CASE PRESENTATION

A female neonatal patient was found to have a 2.97 cm× 1.82 cm×1.50 cm mass with a clear boundary at the right acromion in color Doppler ultrasound examination at 24 weeks of gestation. The mass increased to 3.0 cm×5.0 cm×9.0 cm at birth, and local ulceration was seen. MRI demonstrated that the mass was located on the right shoulder and underarm in a lobulated appearance, and surrounded the right scapula which was deformed. Clinical stage:IV(AJCC 8th Edition (2017)). α-Fetoprofein (AFP) by hematological examination: 1210ng/ml, NSE: 21.28ng/ml, LDH: 842U/L. The patient underwent surgical resection of the tumor, and was pathologically diagnosed as neonatal congenital malignant melanoma; immunohistochemistry (IHC): S-100 (+), HMB45 (+), Melan A (+), and Tyrosinase (+). Molecular pathological examination for BRAF V600E showed no mutations (Quantitative Real-time PCR, qPCR); And so were NRAS, C-kit (exons 9,11,13,14,17,18), and TERT (promoter locus, C228T and C250T) (Sanger sequencing). Non-surgical therapies were not carried out after the surgical resection of the tumor. After 6 months of follow-up, the child developed normally, and color Doppler ultrasound showed no obvious tumor growth or abnormality in the original tumor site.

CONCLUSIONS

It is extremely rare to see giant congenital primary nodular MM in utero in neonates. The pathogenesis, treatment and prognosis of congenital MM need further research. The diagnosis mainly depends on histopathology and immunohistochemistry, and it needs to be differentiated from malignant lymphoma and primitive neuroectodermal tumor. The current treatment strategy for MM relies on the surgical excision of the mass. Research directed at molecular detection for genetic mutations would contribute to targeted therapy and better prognosis.