What are some of the tips to consider when reporting Entamoeba hartmanni?
The measurements of 10 microns or less for the Entamoeba hartmanni cyst refer to wet preparation measurements, so the measurement should be decreased ~1 micron on the permanent stained smear. When you see a cyst on the permanent stained smear, there is often a halo representing shrinkage. The cyst needs to be measured to include that halo. On the bench, the measurements for this cyst generally run from around 9.5 down to about 8 microns and they are morphologically definitely E. hartmanni. The E. hartmanni cyst generally contains more chromatoidal bars than are seen in E. histolytica/E. dispar. Also the E. histolytica/E. dispar cysts tend to measure routinely on the bench (trichrome slides) from about 10.5 up to about 13 or so. Also, on the bench, the E. hartmanni nuclei, particularly in the troph, will tend to look like a “bulls eye” – very sharp line of nuclear chromatin with the karyosome right in the middle.
