Collision Tumor of the Stomach

Abstract

Collison tumor of the stomach is rare, and its endoscopic and pathological features remain poorly described. A 70-year-old woman was referred to our hospital for examination and treatment of undifferentiated gastric cancer. Esophagogastroduodenoscopy revealed a whitish, superficial elevated lesion in contact with a reddish, superficial depressed lesion from the anterior wall of the gastric angle and antrum to the lesser curvature. Laparoscopic distal gastrectomy was performed for preoperative diagnosis of suspected early gastric cancer presenting as a differentiated and undifferentiated collision tumor, which led to the lesion being diagnosed as collision tumor, tub1-tub2+por1-sig, pT1a (M), ly0, v0, N0, stage IA. To our knowledge, this report represents a valuable addition to the collision tumor literature describing a rare case of preoperatively diagnosed collision tumor of the stomach.

Keywords: Collision carcinoma; Collision tumor; Stomach.

Fig. 1

Esophagogastroduodenoscopy. A whitish, superficial elevated lesion (▲) in contact with a reddish, superficial depressed lesion (△) from the anterior wall of the gastric angle and antrum to the lesser curvature on white light imaging (WLI) (a–f).

Fig. 2

Magnifying NBI. An irregular microvascular (MV)/regular microsurface (MS) pattern was shown to be present within the demarcation line in a whitish, superficial elevated lesion (a, b). An irregular MV/irregular MS pattern was shown to be present within the demarcation line in a reddish, superficial depressed lesion (c, d).

Fig. 3

Specimen mapping and histopathologic examination. The differentiated (tub1-tub2) and undifferentiated (por1-sig) gastric cancers were distinctly localized (shown in yellow and red, respectively) (a). Serial sections of the area showed clear boundaries and no histological transition where the two lesions collided (the left and right sides of the dotted line representing tub1 and por1, respectively) (magnification, × 20) (b).