Identification?
Monday, January 14, 2019
Case of the Week 527
This week's case is a good deal more trickier than the last. It was graciously donated by Florida Fan. The patient is a toddler who passed the following 15-cm long worm.
Despite its suggestive outer appearance, the proboscis could not be seen to allow for definitive diagnosis:
Therefore the specimen was sent for histologic sectioning which revealed the following:
In my mind, this is the best use of histologic sectioning for worms - at the direction of the microbiologist, and AFTER the gross specimen has been adequately examined.
Identification?
Identification?
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11 comments:
This is a hard one. It´s very unusual to see a case of Acantocephaliasis in humans. The histologic section reveals a retractable proboscis (with hooks) and neck inside the proboscis receptacle (presoma). It´s difficult to tell the species but probably (given its size) Macracanthorhynchus sp. (M. ingens or M. hirudinaceus) or Moniliformis moniliformis (salient pseudosegmentation).
Acanthocephala with retractile inverted proboscis
I agree with the previous comments. The suggested species are quite reasonable, too.
Macracanthorhynchus or other zoonotic acanthocephalan.
Sparganum spp.
Another rotifer? So soon? ;-)
F.F. did you see any eggs? If so, any comments on size, color, and surface texture of said eggs.
Did patient have any connection with swine?
Rotifer me, Rotifer you
Rotifers in gutland
An evolutionary coup
Old One, this genus rarely sheds eggs in the human host. Sometimes you can cut into the specimen and extract eggs, but often stool OP exams are negative.
If this is a North American case, I'd be more interested in raccoons and millipedes than swine and beetles, as those are the primary definitive and intermediate hosts for M. ingens, the native species in North America. I suspect that most N.A. cases (esp in the East) are M. ingens.
Blaine and Old One:
I poke open the worm, yet did not find an egg. It even did not pop the proboscis out even when pressured: hard headed worm! The only option left was to decapitate the worm, cut it in halves length wise and submit it to mincing by the microtome. There was not a lot of clinical findings provided nor any zoonotic contact. The interesting aspect is that the patient is an 18 months female of Florida, quite a close parallele to a case you had published about two years ago.
Florida Fan
I'll stick to acanthocephala and leave a more precise diagnosis to others.
I've learned Much about the "Thorny Heads".
One thing I do know is that M. hirudinaceus eggs are very resistant. They are known to remain infective for long periods of time and even become fossilized. I had eggs fixed in formalin and stored in 70% ethanol for over 50 years, yet they look as fresh as the day they were born.
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