High-Grade Spindle Cell Sarcoma of the Scalp With an MGA::NUTM1 Gene Fusion in a Pediatric Patient

Abstract

NUT carcinoma (NC) is a rare and aggressive neoplasm associated with a poor prognosis. NC is characterized by a NUTM1- rearrangement on chromosome 15q14, commonly fused with the BRD4 or BRD3 gene . A rare subset of NC defined by fusion of NUTM1 with the MGA gene has been identified, showing mesenchymal differentiation on histology. Few cases of spindle cell sarcomas harboring MGA::NUTM1 gene fusions have been reported in the literature. We describe a case of spindle cell sarcoma harboring an MGA::NUTM1 fusion in a 6-year-old male patient. In contrast to typical cases of spindle cell carcinomas or NC, NUTM1 fusion-positive sarcomas are associated with a better prognosis. This report highlights the importance of diagnostic workup of undifferentiated neoplasms, as identification of the MGA::NUTM1 fusion in spindle cell sarcoma could be used in treatment algorithms and lead to better outcomes, to the benefit of patients.