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

View Article: PubMed Central - PubMed

ABSTRACT

Amebiasis is uncommon in developed countries. Several case reports in the literature emphasize that both the presenting symptoms and the radiological findings of colonic amebiasis closely resemble more common conditions, such as idiopathic inflammatory bowel disease and gastro-intestinal malignancy. We describe a unique case of colonic amebiasis (amebomas) coexisting with signet-ring cell carcinoma of the ileocecal valve, the cecum and the appendix. Endoscopically, the ulcerated tumor was indistinguishable from the ulcerations and pseudotumors (amebomas) detected in the ascending colon. Histological examination of biopsy specimens revealed the pathognomonic features of protozoa with ingested erythrocytes in combination with signet-ring cell infiltration. The author concludes that amebiasis may not only mimic carcinoma but, rarely, may coexist with carcinoma in the same patient. Clinicians and pathologists should be aware of this possibility in order not to delay diagnosis and treatment of malignant disease.

No MeSH data available.


Related in: MedlinePlus

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).
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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).

Mentions: Microscopically, the masses in the ascending colon consisted of necrosis with large amounts of cell debris, desquamated epithelial cells and neutrophils, and extensive inflammatory tissue reaction in the absence of malignancy. Both in the debris and in the submucosal tissues there was evidence of periodic acid-Schiff (PAS)-positive amebas that displayed characteristic features of the invasive pathogen with ingested erythrocytes (Figure 3A-D). Because of the absence of malignancy, the masses in the ascending colon were considered to be amebomas, a complication of chronic amebic disease. Microscopic examination (hematoxylin-eosin and immunohistochemical stains) of biopsy specimens from the ileocecal valve showed amebas intermixed with signet-ring cells infiltrating the submucosa (Figure 3E-J). The CK 7, CK 20 and CDX-2 positive tumor cells, which stained negative with neuroendocrine markers, demonstrated preserved expression of the mismatch-repair proteins MLH1, PMS2, MSH2 and MSH6, indicating a microsatellite stable phenotype of carcinoma.


Diagnosis of colonic amebiasis and coexisting signet-ring cell carcinoma in intestinal biopsy
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).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037093&req=5

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).
Mentions: Microscopically, the masses in the ascending colon consisted of necrosis with large amounts of cell debris, desquamated epithelial cells and neutrophils, and extensive inflammatory tissue reaction in the absence of malignancy. Both in the debris and in the submucosal tissues there was evidence of periodic acid-Schiff (PAS)-positive amebas that displayed characteristic features of the invasive pathogen with ingested erythrocytes (Figure 3A-D). Because of the absence of malignancy, the masses in the ascending colon were considered to be amebomas, a complication of chronic amebic disease. Microscopic examination (hematoxylin-eosin and immunohistochemical stains) of biopsy specimens from the ileocecal valve showed amebas intermixed with signet-ring cells infiltrating the submucosa (Figure 3E-J). The CK 7, CK 20 and CDX-2 positive tumor cells, which stained negative with neuroendocrine markers, demonstrated preserved expression of the mismatch-repair proteins MLH1, PMS2, MSH2 and MSH6, indicating a microsatellite stable phenotype of carcinoma.

View Article: PubMed Central - PubMed

ABSTRACT

Amebiasis is uncommon in developed countries. Several case reports in the literature emphasize that both the presenting symptoms and the radiological findings of colonic amebiasis closely resemble more common conditions, such as idiopathic inflammatory bowel disease and gastro-intestinal malignancy. We describe a unique case of colonic amebiasis (amebomas) coexisting with signet-ring cell carcinoma of the ileocecal valve, the cecum and the appendix. Endoscopically, the ulcerated tumor was indistinguishable from the ulcerations and pseudotumors (amebomas) detected in the ascending colon. Histological examination of biopsy specimens revealed the pathognomonic features of protozoa with ingested erythrocytes in combination with signet-ring cell infiltration. The author concludes that amebiasis may not only mimic carcinoma but, rarely, may coexist with carcinoma in the same patient. Clinicians and pathologists should be aware of this possibility in order not to delay diagnosis and treatment of malignant disease.

No MeSH data available.


Related in: MedlinePlus