This week's case was generously donated by Dr. Emily Snaverly. The following images show an incidental finding from screening colonoscopy, measuring approximately 1cm long. The patient is an asymptomatic, middle-aged male with no known travel history whose previous colonoscopy did not show any parasites. What is your identification?
4 comments:
This is a tapeworm, the proglotids are craspedote being inserted into the anterior one. The rostellum with its hooklets is clearly visible as are two of the sucking discs. The eggs do have hooklets though the polar filaments are not clearly visible, they may be immature. The size of 1cm or 10 mm shows that this a “dwarf” of a tapeworm. Its rodents cousin though called diminuta actually is much longer. Nana for some reason is always shorter. My vote will go for Hymenolepis nana.
Beautiful case, with amazing pictures!!!
Certainly a tapeworm, with an armed rostellum (hooks on its "head"), and suction discs on its scolex - this rules out diphyllobothriid tapeworms.
At first, I was doubting about Taenia solium (armed rostellum) immature worm (causing the eggs to be colorless), but the craspedote positioning of the proglottids, and the large, broad hooks that are visible in the eggs are not really compatible with Taenia.
So I agree with Florida Fan: This is the dwarf tapeworm Rodentolepis nana (also known as Hymenolepis nana). The eggs are still rather immature though, but the shape and size of the hooks are quite typical.
Hymenolepis diminuta (which is kept in the genus "Hymenolepis" in fact) can be ruled out, because of the armed rostellum.
I agree with Idzi. The small size and overlapping proglottids are important clues. Important to point out that the Dwarf Tapeworm (former H. nana / now R. nana) may have an internal autoinfection cyle in the human host leading to persistent / chronic infections.
Fully agree with Idzi and menzler, another clue which is note worthy, is that the proglottids are wider than longer
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