Sunday, December 12, 2021

Answer to Case 664

Answer to the Parasite Case of the Week 664: Hymenolepis (Rodentolepis) nana scolex and egg.

It is very unusual to see a scolex of H. nana; in my experience, it is usually only the proglottids that are removed when seen during colonoscopy. Therefore, it's a real treat to get to see the scolex in an actual clinical specimen! 

Like Taenia solium and Dipylidium caninum, the scolex has an armed rostellum (i.e., protrusion with hooklets). The rostellum of H. nana is generally smaller than that of T. solium, and is often retracted. 

The presence of characteristic H. nana eggs allows for definitive identification. Note the filaments emanating from each pole of the inner membrane.

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