A Clinical, Morphologic, and Molecular Comparison of Bonafide Spitz Melanomas and ASTs in the Pediatric Population.

Pediatric Spitz melanoma (SM) with bonafide metastatic disease is rare. In this study, we assembled the largest cohort to date of pediatric SM with a verified Spitz-associated genomic driver and clinical follow-up demonstrating bonafide metastasis. We compared the clinical, morphologic, and molecular features of these SMs to a control cohort of 57 pediatric atypical Spitz tumors (ASTs).

NSD3::FGFR1: A Novel Gene Fusion First to Be Described in Merkel Cell Carcinoma.

Merkel cell carcinomas (MCCs) exhibit diverse molecular profiles, often categorized by their association with Merkel cell polyoma virus (MCPyV). MCPyV-associated MCCs typically display a low tumor mutational burden (TMB), lacking both somatic mutations and ultraviolet signature. By contrast, MCPyV-negative MCCs commonly arise in sun-exposed skin and frequently exhibit a high TMB, along with TERT promoter mutation (TPM) and somatic mutations, particularly in TP53 and RB1.

BRCA1-Associated Protein-1 Inactivated Melanoma Arising in a Pre-existing Nevus With ALK Fusion and Low Tumor Mutational Burden.

Breast cancer1-associated protein 1 (BAP-1)-inactivated melanocytic tumors are a group of familial or sporadic lesions with distinctive histology and molecular features. Inherited germline inactivating mutations in BAP1 have been associated with the development of multiple epithelioid melanocytic neoplasms resembling Spitz nevi and increased susceptibility for developing several malignancies, including uveal melanoma, cutaneous melanoma, renal cell carcinoma, mesothelioma, and other tumors. Cutaneous melanoma with loss of BAP1 expression is rare.

Nicotinic Acetylcholine Receptor Expression in Merkel Cell Carcinoma Is Associated With Clinical and Histopathologic Parameters.

Background: Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous malignancy with neuroendocrine differentiation. Several molecular pathways have been implicated in MCC development and multiple cell-of-origin candidates have been proposed, including neural crest cells, which express acetylcholine receptors (AChRs). The role of nicotinic acetylcholine receptors (nAChRs) in MCC has not been explored.