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8 November 2012 - Case of the Week #257

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Thanks to Dr. Josemari Arrinda Yeregui, Bidasoa Hospital (Spain), for contributing this case and the discussion. To contribute a Case of the Week, follow the guidelines on our Case of the Week page.

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Website news:

(1) Our Feature Page for November highlights Consumable Lab Products / Clinical Lab Analyzers, and includes Leica Microsystems, Sakura Finetek USA and Ventana Medical. We also have a new Mystery Case on the right side of the Home Page.

(2) We have updated the Fibrohistiocytic section of the Soft Tissue chapter, based on reviews by Vijay Shankar, M.D.

(3) We have changed the name of a chapter from Management-Laboratory to Laboratory Administration to avoid confusion with the Management of pathology practices chapter.

Case of the Week #257

Clinical History:

A 50 year old man presented with watery diarrhea for 12 months. Endoscopy was suggestive of Crohn's disease of the right colon.

Micro images:


What is your diagnosis?


Intestinal spirochetosis and amebiasis


Microscopically, many Entamoeba histolytica trophozoites are seen, as well as a blue hazy barrier at the mucosa. This barrier is highlighted with PAS (above) and with anti-Treponemal Pallidum antibody (below):


Human intestinal spirochetosis is defined histologically by the presence of spirochetal microorganisms attached to the apical cell membrane of colorectal epithelium (Ger Med Sci 2010;8:Doc01).

Human intestinal spirochetes include Brachyspira aalborgi and Brachyspira pilosicoli. Incidence is common in poorly developed areas, but low where living standards are high. Homosexuals and HIV+ individuals are at high risk. Most patients are asymptomatic, but children, homosexual and HIV+ men are more likely to be symptomatic regardless of invasion. The bacteria can be highlighted using silver stains, PAS, Giemsa, Alcian-blue (pH 2.5) and by immunohistochemistry (Colon-nontumor chapter).

Intestinal spirochetosis often coexists with other enteric pathogens, including Entamoeba histolytica (J Gastroenterol Hapatol 2007;22:64), Enterobius vermicularis, Helicobacter pylori, Shigella flexneri and Neisseria gonorrhoeae. Amebic colitis (amebiasis) resembles inflammatory bowel disease, but is caused by Entamoeba histolytica protozoa. It may cause dysentery, colonic stricture, ulceration and perforation, liver abscesses up to 10 cm or be asymptomatic (Colon-nontumor chapter). Transmission is by fecal-oral spread, with increased incidence in homosexuals, patients with AIDS or from the tropics.

The patient was treated with metronidazole, which covers both pathogens, which eliminated the diarrhea. The patient was subsequently diagnosed as HIV+.

Nat Pernick, M.D., President
and Palak Thakore, Associate Medical Editor
PathologyOutlines.com, Inc.
30100 Telegraph Road, Suite 408
Bingham Farms, Michigan (USA) 48025
Telephone: 248/646-0325
Email: NatPernick@Hotmail.com
Alternate email: NatPernick@gmail.com