Diagnosis of colonic amebiasis and coexisting signet-ring cell carcinoma in intestinal biopsy

Figure 3 Microscopic examination. A, B: Microscopy (A: HE stain, × 20, B: PAS, × 20) of biopsy specimens from the ascending colon showing aggregations of round PAS-positive Entamoeba histolytica trophozoites within cell debris; C, D: High power view (C: HE stain, × 40, D: PAS, × 20) demonstrating PAS-positive trophozoites containing ingested erythrocytes (arrow in C); E, F: Microscopy (HE stain, × 20) of biopsy specimens from the ileocecal valve showing infiltrating signet-ring cells (arrows in E) in combination with amebic protozoa (arrow in F); G-J: The tumor cells stain positive with pancytokeratin (G: × 20), CK 7 (H: × 20), CK 20 (I: × 20) and CDX-2 (J: × 20).