MAP2K1-Mutated Melanocytic Neoplasms With a SPARK-Like Morphology

Area of Science:

• Oncology
• Dermatopathology
• Molecular Pathology

Background:

• Specific MAPK pathway gene alterations (MAP3K8, MAP3K3 fusions) are identified in a subset of spitzoid neoplasms.
• These neoplasms often present in younger individuals with atypical histology and CDKN2A deletion, aligning with Spitz melanoma.
• Previous research noted a single case of MAP2K1 deletion in spitzoid lesions.

Purpose of the Study:

• To investigate melanocytic lesions with MAP2K1 mutations.
• To characterize the clinicopathologic and histologic features of these MAP2K1-mutated lesions.
• To determine if MAP2K1 mutations define a distinct clinicopathologic group.

Main Methods:

• Retrospective analysis of melanocytic lesions.
• Histopathologic examination including cytology and architectural features.
• Molecular analysis to identify MAP2K1 mutations.

Main Results:

• Four melanocytic lesions with MAP2K1 mutations were identified.
• These lesions exhibited consistent microscopic features: spitzoid cytology and dysplastic architectural changes.
• The observed features resemble those of SPARK nevus.

Conclusions:

• MAP2K1 mutations may define a distinct group of melanocytic neoplasms.
• These lesions share microscopic similarities with SPARK nevus.
• Further research is warranted to fully elucidate the significance of MAP2K1 mutations in spitzoid neoplasms.