《Slide 41.》Amebiasis, Colon

A. Brief Descriptions：

1. Caused by the protozoan parasite Entamoeba histiolytica.

2. Infections from---E. histiolytica cysts (achitin wall & 4 nuclei).                                       

3. Ameboid from----trophozoites.

4. Most frequently involves the cecum and ascending colon followed by sigmoid à rectum à appendix.

B. Gross Findings：

      略.

C. Micro Findings：

1. Ulcerated mucosa, edema, congestion and a prominent infiltrate of eosinophils.

2. Round organisms of 20-40 um diameter, some ingested RBCs (erythrophagocytosis ), are found in loose surface debris.

D. Others:

1. Diagnosis is best made by identified hematophagous trophozoites in fresh stools.

E. Reference：

1. Robbins Pathologic Basis of Disease, 6^th ed.  P.358-359.

　

 

 

【 Fig. 41-1 (LP)】Numerous eosinophilic spherical structure within necrotic area.

　

　

 

【 Fig. 41-2 (HP)】The spherical structure (trophozoites) has one basophilic

                                                       nuclei about the size of RBC’s. Note some RBCs are

                                                       phagocytized by the trophozoites (erythrophagocytosis).