Figure 4. (A) Gross image of the left splenic flexure colonic mass. The mass is ulcerated and measures 4.5×4.0×1.5 cm. A low-magnification microscopic image of the colonic mass (moderately differentiated colonic adenocarcinoma). There are infiltrating, atypical glands with desmoplastic reaction. (B) The tumor extends into the pericolic adipose tissue. A higher-magnification microscopic image of the colonic mass. (C) Extensive surface erosion with inflammatory exudate also is present, which suggests ulceration. Unremarkable colonic mucosa (arrow) is adjacent to the infiltrative tumor cells. (D) The tumor is composed of infiltrating, atypical glands with large nuclei and focal luminal necrosis along with a desmoplastic reaction, consistent with moderately differentiated colonic adenocarcinoma.