Malignant Esophageal Glomus Tumor With CARMN::NOTCH2 Fusion: An Additional Tumor Underscoring the Frequent Tendency of Esophageal Glomus Tumors for Aggressive Behavior.

Malignant glomus tumors are rare tumors of pericytic origin with a propensity to develop in the upper gastrointestinal tract. Hereby we demonstrate a tumor of a 20-year-old man, who presented with dysphagia and an exophytic esophageal mass. Histologic examination of the resected mass revealed a multinodular tumor in the esophageal wall composed of epithelioid cells showing nesting and monomorphic atypia, staghorn vessels and scanty stroma. Immunohistochemically, the neoplastic cells were positive for SMA, and H-caldesmon, while desmin was negative. Collagen IV and laminin decorated a dense intercellular basal membrane meshwork. RNA-sequencing using TruSight RNA Pan-Cancer Panel revealed a CARMN::NOTCH2 fusion, that is a recurrent, frequently described and so far specific genetic alteration in glomus tumors. In spite of the adjuvant chemotherapy regimens, the patient died of disseminated metastatic disease 2 years after the diagnosis. Our patient presentation and the previous reports in the literature highlight the frequently aggressive behavior of glomus tumors arising in the esophagus.