DOG1 is useful for diagnosis of KIT-negative gastrointestinal stromal tumor of stomach

Figure 1 Findings on upper gastrointestinal endoscopy. A submucosal tumor accompanied by an ulcer with an adherent clot was found in the superior portion of the anterior wall of the gastric antrum.

Figure 2 Findings on upper endoscopic ultrasonography. A homogeneous, hypoechoic, well-demarcated mass, approximately 4 cm in diameter with a flat border, arising from the fourth layer of the gastric wall.

Figure 3 Histopathological findings of the surgically resected specimen. A: Hematoxylin and eosin staining (× 100). The tumor consisted of mixed components, including spindle cells with eosinophilic cytoplasm, as well as epithelioid cells in some regions; B: KIT staining (× 100), KIT staining was negative; C: CD34 staining (× 100), CD34 staining was negative; D: Vimentin staining (× 100); vimentin staining was positive. E: Smooth muscle actin (SMA) staining (× 100), SMA staining was negative; F: DOG1 staining (× 100); Immunostaining for DOG1 was positive mainly in the cell membrane and cytoplasm. DOG1: Discovered on gastrointestinal stromal tumor-1.

Figure 4 Histopathological findings (specimen obtained by endoscopic ultrasound-guided fine needle aspiration biopsy). A: Hematoxylin and eosin staining (× 100).The tumor consisted of mixed components, consisting of spindle cells with eosinophilic cytoplasm, as well as cells with epithelioid features in some regions; B: KIT staining (× 100), KIT staining was negative; C: DOG1 staining (× 100). Immunostaining for DOG1 was positive mainly in the cell membrane and cytoplasm. DOG1: Discovered on gastrointestinal stromal tumor-1.