Fig. 1

a Contrast-enhanced CT findings revealed a large submucosal mass approximately 180 mm in length, contiguous with the transverse to descending colon. Heterogeneous contrast images were visible within the mass. b PET-CT demonstrated FDG accumulation (SUVmax: 9.42) within the mass, with no evidence of obvious abnormal accumulation elsewhere. c The resected intra-abdominal tumor was 260 × 250 × 120 mm in size and weighed approximately 3.5 kg. d The cut surface of the mass was grayish-white, with a circumscribed surface, and an extramural growth from the transverse colon. Mucinous degeneration was observed in certain areas along with a certain degree of bleeding