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Case #346 - April, 2013

A 21-year-old exchange student from Nepal sought medical attention for intermittent diarrhea associated with mild abdominal cramps. A stool specimen was collected for laboratory testing in low viscosity polyvinyl alcohol (LV-PVA). A smear was made from the preserved stool and stained with trichrome. Figures A-D show what was observed in moderate numbers at 1000x magnification with oil; Figures A and B show the same object in different focal planes. The size of the objects ranged from 15-20 micrometers in diameter. What is your diagnosis? Based on what criteria?

Case346_A

Figure A

Case346_B

Figure B

Case346_C

Figure C

Case346_D

Figure D

Case Answer

The organisms observed were cysts of Entamoeba polecki, which is generally considered to be a nonpathogenic amoeba that can reside in the large intestine. Morphologic features shown included:

  • cysts within the size range (9-24 micrometers) for the species.
  • the presence of a large, irregular nucleus with a pleomorphic karyosome.
  • the presence of numerous irregular, red-staining chromatoid bodies.

More on:Entamoeba polecki

Images presented in the monthly case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.

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DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/.

  • Page last reviewed: August 24, 2016
  • Page last updated: August 24, 2016
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