Myoepithelioma-like tumor of the vulvar region with estrogen receptor negativity and GSTT1::IGLC7 fusion: a case report.

Myoepithelioma-like tumor of the vulvar region (MELTVR) is a rare mesenchymal neoplasm that exhibits morphological features resembling those of soft tissue myoepitheliomas, yet displays distinct immunophenotypic and molecular genetic characteristics. All MELTVR cases reported in the existing literature have been estrogen receptor (ER)-positive. In contrast, this study presents the first documented case of ER-negative MELTVR, thereby broadening the known immunohistochemical phenotypic spectrum of this neoplasm. Next-generation sequencing (NGS) analysis revealed copy number loss of SMARCB1 and a novel GSTT1::IGLC7 fusion in the tumor, while no other gene rearrangements, including those involving EWSR1, NR4A3, or FUS, were detected. This finding not only expands the molecular genetic spectrum of MELTVR but also provides valuable insight for future investigations into its pathogenesis, biological behavior, and refinement of clinical diagnostic and therapeutic strategies for this rare tumor.