Fig. 4
a Mucinous adenocarcinoma showing a few profiles of conventional malignant colonic acini associated with pools of extracellular mucin. (H&E; original magnification × 40). b Medullary carcinoma showing groups of polygonal cells with vesicular nuclei, prominent nucleoli and abundant cytoplasm arranged in a diffuse or nesting pattern. (H&E; original magnification × 40). c Signet ring cell carcinoma showing a predominance of dyscohesive cells with prominent intracytoplasmic mucin and a crescentic nucleus that is displaced to one side. (H&E; original magnification × 40). d Goblet cell carcinoma (grade 1) composed of small well-defined nests of goblet-like cells. Immunohistochemistry showed scattered neuroendocrine cells within the goblet cell clusters. Other areas showed Paneth cell differentiation. (H&E; original magnification × 40)