Yunus KAYCI, Serdar GÜMÜŞ, Uğur TOPAL, İshak AYDIN, Zülfi ZAHİDLİ, Halil GÜNEŞ, Çağla DURU, Kıvılcım Eren ATEŞ, Cem Kaan PARSAK
Çukurova Anestezi ve Cerrahi Bilimler Dergisi - 2026;9(3):765-770
Introduction: Extraosseous osteosarcoma (ESOS) is a rare soft-tissue sarcoma that produces osteoid without anatomical relationship to the skeleton. Primary gastric ESOS is exceptionally rare and poses major diagnostic and therapeutic challenges. Case Presentation: A 78-year-old man with six months of nonspecific gastrointestinal symptoms had a 14 x 16 x 21 cm gastric mass with extensive local involvement. Endoscopic ultrasound-guided fine-needle aspiration was non-diagnostic. After massive upper gastrointestinal hemorrhage with hemodynamic instability, emergency laparotomy and R2 debulking were performed. Histopathology showed a high-grade osteoid- and chondroid-producing malignant mesenchymal tumor; SATB2 was positive. PET-CT showed no skeletal primary, supporting gastric ESOS. Conclusion: Primary gastric ESOS may present as a giant locally invasive mass with non-diagnostic biopsy. Complete resection should be pursued when feasible, while emergency presentation may necessitate non-curative surgery.
