MEIS1::NCOA2 Fusion Sarcoma of the Bartholin Gland: A Case Report and Review of the Literature

Background: MEIS1::NCOA1/2 fusion sarcomas are a recently described molecular entity arising predominantly in the genitourinary and gynecologic tracts. Their clinical presentation is often misleading, and no standardized treatment guidelines currently exist. Methods: A literature review was conducted using PubMed to identify all reported cases of molecularly confirmed MEIS1::NCOA1/2 fusion sarcomas. Clinicopathological, molecular, treatment, and outcome data were extracted for comparative analysis. Case: We report the case of a 38-year-old nulliparous woman who presented with a right vulvar induration clinically consistent with a Bartholin gland cyst. Surgical excision revealed a spindle cell mesenchymal tumor harboring a MEIS1::NCOA2 fusion transcript and a CTNNB1 exon 3 mutation, with probable incomplete resection margins. A local recurrence was documented by MRI and PET–CT at eight months. Surgical re-excision revealed diffuse involvement and complete excision was considered uncertain. Adjuvant external beam radiotherapy followed by an MR-Linac boost was administered. Discussion: This case highlights the diagnostic challenge of Bartholin gland masses. We provide a review of the literature on MEIS1::NCOA1/2 fusion sarcomas and examine the potential aggressiveness of tumors that additionally harbor a CTNNB1 mutation. Given the nonspecific immunophenotype of this entity, this case underscores the indispensable role of RNA-based molecular sequencing in the diagnosis of low-grade spindle cell tumors when immunohistochemistry proves inconclusive. We further discuss the surgical challenges inherent to this anatomical region and explore intention-to-treat radiotherapy as a potential therapeutic option. Conclusions: We report a rare case of a MEIS1::NCOA2 fusion-positive sarcoma arising in the Bartholin gland region, and, to our knowledge, the first case in which radiotherapy with curative intent has been explored for this entity. This observation expands the limited literature on this emerging clinicopathological entity.