Answer: Consistent with Dipylidium caninum proglottids.
These small white-tan proglottids can appear as "grains of rice" and "cucumber seeds." They are often noted by the caregiver in the patients stool (usually a young child) due to their motility. I've shown various examples of D. caninum proglottids in previous cases, which demonstrate the size and mild variability in shape that may be observed:
Case 188 shows a nice example of "rice grain" morphology while
Case 107 shows a more characteristic appearance of a "cucumber seed"
In order to confirm the diagnosis, the proglottids should be manipulated to express eggs for examination. The fluid or stool submitted with the proglottids should also be examined for eggs. Examples of characteristic eggs can be seen in both of the cases above. In rare cases when eggs are not forthcoming, the proglottids can undergo histologic sectioning.