Giardiasis

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Giardiasis
Diagnosis in short

Giardiasis. H&E stain.

LM flagellate protozoa - pale/transluence on H&E, 12-15 micrometers (long axis) x 6-10 micrometers (short axis); +/-loss of villi, intraepithelial lymphocytes, inflammatory cells - especially close to the luminal surface
LM DDx celiac disease
Stains methylene blue +ve
IHC CD117 +ve (microorganisms)
Site duodenum

Signs diarrhea x5 days, foul smelling feces, flatulence
Symptoms fatigue, abdominal cramps, nausea
Prevalence uncommon
Endoscopy +/-white spots, diffuse changes
Prognosis good, benign
Clin. DDx celiac disease, other causes of diarrhea
Treatment antibiotics

Giardiasis is a rare infection, classically found in the duodenum. It can mimic celiac disease. It is also known as beaver fever.

General

Clinical features - usually two or more of the following:[1]

  • Diarrhea - x5 days.
  • Flatulence.
  • Foul smelling feces.
  • Nausea.
  • Abdominal cramps.
  • Excessive tiredness.

Epidemiology:

  • Uncommon.

Etiology:

  • Flagellate protozoan Giardia lamblia.

Treatment

  • Antibiotics, e.g. metronidazole (Flagyl).

Gross

  • Diffuse changes.
  • May have scattered white spots.[2]

Microscopic

Features:

  • +/-Loss of villi.
  • Intraepithelial lymphocytes.
    • +Other inflammatory cells, especially PMNs, close to the luminal surface.
  • Flagellate protozoa -- diagnostic feature.
    • Organisms often at site of bad inflammation.
    • Pale/translucent on H&E.
    • Size: 12-15 micrometers (long axis) x 6-10 micrometers (short axis) -- if seen completely.[3]
      • Often look like a crescent moon (image of crescent moon) or semicircular[4] -- as the long axis of the organism is rarely in the plane of the (histologic) section.

Note:

  • Changes are typically diffuse, i.e. if multiple biopsies are done the changes are present in all fragments.[5]

DDx:

Images

www:

Stains

  • Methylene blue +ve.[6]

IHC

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A. Duodenum, Biopsy:
- Abundant micro-organisms consistent with GIARDIA and small 
  bowel mucosa with increased intraepithelial lymphocytes, see comment.
- NEGATIVE for dysplasia.

B. Stomach, Biopsy:
- Body and antral-type mucosa with mild chronic inactive inflammation.
- NEGATIVE for Helicobacter-like organisms.
- NEGATIVE for intestinal metaplasia.
- NEGATIVE for dysplasia and NEGATIVE for malignancy.

Comment:
The increased intraepithelial lymphocytes are likely to due to the Giardia; however, other 
causes cannot be excluded.

Block letters

DUODENUM, BIOPSY:
- SMALL BOWEL MUCOSA WITH BRUNNER'S GLANDS AND MICROORGANISMS CONSISTENT WITH GIARDIA.

See also

References

  1. Hopkins, RS.; Juranek, DD. (Feb 1991). "Acute giardiasis: an improved clinical case definition for epidemiologic studies.". Am J Epidemiol 133 (4): 402-7. PMID 1994703.
  2. Biyikoğlu, I.; Babali, A.; Cakal, B.; Köklü, S.; Filik, L.; Astarci, MH.; Ustün, H.; Ustündağ, Y. et al. (Nov 2009). "Do scattered white spots in the duodenum mark a specific gastrointestinal pathology?". J Dig Dis 10 (4): 300-4. doi:10.1111/j.1751-2980.2009.00399.x. PMID 19906109.
  3. http://www.water-research.net/Giardia.htm
  4. http://en.wikipedia.org/wiki/Semicircle
  5. Freeman, HJ. (Mar 2008). "Pearls and pitfalls in the diagnosis of adult celiac disease.". Can J Gastroenterol 22 (3): 273-80. PMID 18354756.
  6. Rajurkar, MN.; Lall, N.; Basak, S.; Mallick, SK. (Nov 2012). "A simple method for demonstrating the giardia lamblia trophozoite.". J Clin Diagn Res 6 (9): 1492-4. doi:10.7860/JCDR/2012/4358.2541. PMID 23285438.
  7. Sinelnikov, I.; Sion-Vardy, N.; Shaco-Levy, R. (Mar 2009). "C-kit (CD117) immunostain is useful for the diagnosis of Giardia lamblia in duodenal biopsies.". Hum Pathol 40 (3): 323-5. doi:10.1016/j.humpath.2008.07.015. PMID 18835628.