Homo sapiens Variation

we reported a patient, harboring a huge abdominal mass, was initially diagnosed as an epithelioid gastrointestinal stromal tumor (GIST) via biopsy pathology due to CD117 immunohistochemical expression and detection of KIT mutation in exon 17 (p.Y823D). After first- to fourth-line targeted therapies, the patient exhibited rapid tumor progression, promoting diagnostic reevaluation. Definitive diagnosis of seminoma was established through expanded immunohistochemistry (OCT4+/SALL4+/PLAP+/D2-40+) and molecular confirmation of the characteristic KIT p.D816Y mutation, which concurrently explains the observed imatinib resistance.