Lethal melanoma in children: a clinicopathological study of 12 cases

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.

Spitz Melanoma of Childhood With A Novel Promoter Hijacking Anaplastic Lymphoma Kinase (C2orf42-ALK) Rearrangement

ABSTRACT

We present the case of a prepubescent man of African descent who developed a spitzoid melanocytic proliferation showing evidence of a novel promoter hijacking ALK-C2orf42 rearrangement, with atypical histology, clinically apparent metastatic disease, and abnormal cytogenetic findings, representing a rare genuine case of "Spitz melanoma of childhood." As our understanding of the distinct molecular biology of different tumors traditionally grouped as spitzoid melanocytic lesions evolves, it is becoming increasingly apparent that this group encompasses morphologically and genetically distinct entities. Accurate classification with detailed molecular analysis and prolonged clinical follow-up is essential to allow meaningful conclusions regarding prognostication and prediction of response to therapy.

Mechanism of MicroRNA-708 Targeting BAMBI in Cell Proliferation, Migration, and Apoptosis in Mice With Melanoma via the Wnt and TGF-β Signaling Pathways

Objective:

The aim of this study was to evaluate the mechanisms involved with miRNA-708 and its targeting of bone morphogenetic protein and activin membrane-bound inhibitor in cell proliferation, migration, and apoptosis in mice with melanoma via the Wnt and transforming growth factor β signaling pathways.

Methods:

Sixty mice were recruited of which 40 were subsequently assigned into the experimental group (22 mice were successfully established as melanoma model and 18 mice used in tumor xenograft), and the normal control group consisted of 20 mice. B16 cells were assigned to the normal, blank, and negative control, miR-708 mimics, miR-708 inhibitors, si-BAMBI, and miR-708 inhibitors + si-bone morphogenetic protein and activin membrane-bound inhibitor groups. Western blotting and reverse transcription quantitative polymerase chain reaction were employed to detect the expression levels within the tissues and cell lines. TCF luciferase reporter (TOP-FLASH) or a control vector (FOP-FLASH) was applied to detect the activity of the Wnt signaling pathway. MTT3-(4,5-Dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide assay, flow cytometry, scratch test, and Transwell assay were conducted, respectively, for cell proliferation, apoptosis, migration, and invasion, while tumor xenograft procedures were performed on the nude mice recruited for the study.

Results:

Compared to the normal control group, the model group displayed increased expressions of bone morphogenetic protein and activin membrane-bound inhibitor, Wnt10B, P53, and Bcl-2; TOPflash activity; β-catenin expression; cell proliferation; migration; and invasion capabilities while decreased expressions of miR-708, vascular endothelial growth factor, Fas, Bax, Caspase-3, and cleaved Caspase-3 and apoptosis rate. Compared to the blank and negative control groups, the miR-708 mimics and small-interfering RNA-bone morphogenetic protein and activin membrane-bound inhibitor groups exhibited decreases expressions of bone morphogenetic protein and activin membrane-bound inhibitor, Wnt10B, P53, and Bcl-2 and decreased proliferation, migration, and invasion capabilities, while increases in the apoptosis rate, expressions of vascular endothelial growth factor, Fas, Bax, Caspase-3, and cleaved Caspase-3; however, downregulated levels of TOPflash activity and β-catenin expression were recorded. The miR-708 inhibitors group displayed an opposite trend.

Conclusion:

Downregulation of miR-708-targeted bone morphogenetic protein and activin membrane-bound inhibitor inhibits the proliferation and migration of melanoma cells through the activation of the transforming growth factor β pathway and the suppression of Wnt pathway.

Common and not so Common Melanocytic Lesions in Children and Adolescents

The acquired melanocytic nevus is the most common lesion encountered by pediatric pathologists and dermatopathologists in their daily practice. In most cases, there are few difficulties in histopathologic diagnosis. However, it is the acquired melanocytic lesion known as the Spitz nevus, with its intrinsic atypical features which becomes the challenge since it exists along a histopathologic and biologic continuum from the atypical Spitz tumor to spitzoid melanoma. The frustration with some of these spitzoid lesions is that even the "experts" cannot agree as to the differentiation of one from the other even at the level of molecular genetics. Other melanocytic lesions are discussed including the congenital melanocytic nevus with its proliferative nodule(s) and melanoma as the ultimate complication. Although uncommon, cutaneous melanoma in the first 2 decades is emerging as a clinical problem especially in young women in the second decade of life. These are ultraviolet-associated neoplasms whose histopathologic and prognostic features are identical to the adult experience. Considerable progress has been made over the past 15 to 20 years in our understanding of cutaneous melanocytic lesions, but gaps still exist in the important group of spitzoid lesions. It can also be anticipated that more cutaneous melanomas in children will be seen in the future based upon epidemiologic studies.

Pathology and genomics of pediatric melanoma: A critical reexamination and new insights

The clinicopathologic features of pediatric melanoma are distinct from those of the adult counterpart. For example, most childhood melanomas exhibit a uniquely favorable biologic behavior, save for those arising in large/giant congenital nevi. Recent studies suggest that the characteristically favorable biologic behavior of childhood melanoma may be related to extreme telomere shortening and dysfunction in the cancer cells. Herein, we review the genomic profiles that have been defined for the different subtypes of pediatric melanoma and particularly emphasize the potential prognostic value of telomerase reverse transcriptase alterations for these tumors.