Gastroblastoma Treated by Endoscopic Submucosal Excavation with a Novel PTCH1::GLI2 Fusion: A Rare Case Report and Literature Review

Gastroblastoma is an extremely rare stomach tumor that primarily presents in adolescent and early adulthood, with a biphasic cell morphology of epithelioid and spindle cells. In light of its similarity to other childhood blastomas, it has been named gastroblastoma. Few patients showed a potential of metastasis and recurrence, however, most of the reported cases were alive, with no evidence of the disease after surgical treatment. Commonly, MALAT1-GLI1 fusion has been considered to be the most relevant mutation. Herein, we present a case of an asymptomatic 58-year-old man who happened to find a submucosal gastric mass during a gastroscope and received endoscopic submucosal excavation (ESE). He turned out to have a gastroblastoma with a novel PTCH1::GLI2 fusion confirmed by Sanger sequencing. The patient was discharged two days after ESE without any complication and was recurrence-free during his one-year follow-up. According to the previous literature and our own experience, in cases with characteristic histopathology and immunohistochemistry patterns, a diagnosis of gastroblastoma should be considered even without a MALAT1-GLI1 fusion. Gastroblastoma pursues a favorable clinical outcome and endoscopic therapy could be an effective alternative treatment choice.