Answer to Case 699

Answer: Clonorchis sinensis/Opisthorchis eggs. The location (South Korea) is consistent with C. sinensis.

As noted by Sam, "Both eggs have an abopercular knob and an obvious operculum. So these could be eggs of either Clonorchis sinensis or Opisthorchis species (both liver flukes). We can't differentiate based on morphology, but based on the patient being from/living in South Korea, we can likely narrow the identification down to Clonorchis sinensis, as Korea is an endemic region for this parasite. Whereas Opisthorichis viverrini is endemic to South East Asia (i.e, Vietnam, Cambodia, Laos, Thailand). Biliary complications can arise from long term Clonorchis sinensis infections, including cholangiocarcinoma."  Other complications, as noted by Eddy Martinez, are cholangitis, cholelithiasis, cholecystitis, and pancreatitis. The shouldered operculum and small size of the eggs (around 30 micrometers long) are nicely appreciated in this case:

The eggs of Metagonimus yokogawai and Heterophyes heterophyes also have a similar appearance and should be considered in the differential diagnosis. They are not found in South Korea, however, and can be excluded in this case.