Case 21. Ameboma in AIDS (35 y-o M)
　 　 　 　 　
　 　 Cecum from a single male surgically resected under the diagnosis of colon cancer 　 　
　 　 　 　 　
　 　
Key words : Entamoeba histolytica, ameboma, AIDS, colitis, Balantidium coli
 　 　
　 　 　 　 　
　 　
opportunistic infection, sexually transmitted infection
 　 　
　 　 　
　
　 　 　
Colon cancer-like tumor formation caused by amebic infection (gross findings) 　 Trophozoites seen in ulcer base necrotic debris (HE, low power)
　 　 　
　
　 　 　
Trophozoites seen in ulcer base necrotic debris (HE, high power) 　 Reference case 21A
 Mixed infection of E. histolytica and G. lamblia in rectal lavage (30 y-o M, AIDS patient).　Both protozoan species often cause "gay bowel syndrome" in AIDS patients (Giemsa).
　 　 　
　
　 　 　
Reference case 21B
 Amebic colitis, surgically resected from the aged (75-y-o M).　Ulcer base showing dirty inflammatory reaction (gross findings).		 　 Reference case 21B
 Amebic colitis, surgically resected from the aged (75-y-o M).　A flask-shaped ulceration with intact proper muscle layer (HE, low power).
　 　 　
　
　 　 　
Reference case 21B
 Amebic colitis, surgically resected from the aged (75-y-o M).　Amebic trophozoites in the ulcer base are PAS-positive.		 　 Reference case 21B
Amebic colitis, surgically resected from the aged (75-y-o M).　The trophozoites are clearly decorated with a monoclonal antibody (immunostaining).
　 　 　
　
　 　 　
Electron micrograph of E. histolytica
Cultured trophozoites showing cytoplasmic vacuolation and characteristic chromatin distribution in the nucleus.　Anerobic E. histolytica totally lacks mitochondria.		 　 Reference case 21C
Balantidium coli in the stool, showing a ciliated trophozoite.　The large ciliated trophozoite up to 100 μm contains a large bean-shaped nucleus (Gomori's trichrome).
　 　 　
　 　
　 　 　
Reference case 21C
Balantidium coli invading the submucosa of pig colon.　This ciliophora may invade the colonic wall, provoking dysentery-like clinical features in pig, and rarely in human.