Blastocysts of trypanorhynch tapeworms? Or tissue parasitizing didymozoid trematodes? Or encapsulated nematodes (Anisakidae?)?

I would say cysts/capsules of metazoan endoparasite stages...

Jalil, trying to answer your query based on this photo would have to be mainly guesswork. You would really need to post a microscope magnification of one of the focal lesions and anything that might be inside it. 

Maybe, this file would be useful for diagnosis.

Regards

Dear Dr Zorriehzahra

I also think we need histopathological photo- micrograph for final diagnosis of these lesions. But according this image my tentative diagnosis  is parasitic cysts. 

Best Regards,

A. Amniattalab

Dear  Dr. Amir,

Please see attached file in above comment.

Regards

Did you observed the squash of the sample under microscope or cultured the sample for microbial examination that will reveal the nature of disease? May be parasites affecting (Myxozoans).

Dear Dr. Jalil

I saw your attached file. Do you have a higher magnification image related to cystic space wall?

I agree with the rest. Looking at one picture is not enough to make a diagnosis. At least take one of the postule-like  lesion and look at it in the microscope. Is there something inside that rotten-like hole? Are there any dominant bacteria in it? 

I am not a microbiologist, but those questions comes to mind.

Dear Jalil

I agree with Thomes Kuhn apparently conditions are quite identical to nematode parasitic encystment but require physical confirmation.

The histopatho image doesnt look like a helminth. But maybe this one was degenerated. Maybe better to check a few more under LM and also histopatho.

Dear Jalil,

I agree with the others that it is difficult to make a diagnosis at the resolution and magnification of the photo and the photomicrograph of the histological section. Have any special stains (e.g. Giemsa, Gram, etc.) been done for histological sections?

Dear Jalil,

It is encysted, and if a parasite at all, it would be likely a larval stage. Two things can be done to identify this further:

1. More histopath as suggested by the earlier respondents - best done on a freshly dead specimen, i.e almost immediately after death if possible or at least on chilled specimens within several hours of death.

2. Digest out the parasites - you should be able to locate a suitable method in a standard parasitological text or website. Juvenile larval stages may not have all the identifying features present in adult worm, which is sometimes needed for identification but it should certainly help you at least identify whether it is a nematode, trematode or cestode. I suspect that it may be a trematode larvae of some sort, and histology and digesting out larval may bring you a step closer to idenifying this.

Susan Gibson-Kueh

Dear respected colleagues,

Let me appreciate all of you for your valued responses.

I asked from my friend Dr. Giuseppe more Histopathological pictures from mentioned lesions with higher magnification.

If I found more pictures I will share it with you immediately.

Let me appreciate all of you again.

Kindly regards

After saving the image and zooming in a bit, I suspect it's a helminth cyst (metacercaria or nematode) given the "roundedness" of the cyst. That said, the contents shown in the attached histo pic  from Jalil) are relatively uniform throughout. Dissect one of them.

Hi Jalil,

If you can get more histology images, there should be good texts or articles on identifying these critters. Even general parasitology texts will make good reference. Fish parasites may be of different species, but all trematodes, cestodes or nematodes share common features whether from fish, terresterial animals or birds.

In particular, histopathologically both trematodes and cestodes will not have a body cavity or coelom, only mainly gut and reproductive organs sitting in loose connective tissues. Nematodes will have a body cavity in which the internal organs sit. Only it can be a bit tricky top decide whether a coelom or body cavity exists or not sometimes.

And if these larvae stages can be dissected out, then they can be identififed as cercariae or possibly cestode larvae, or nematode larvae.

Good luck, and I hope you identify these cysts soon.

Susan

I agree with most of the comments above regarding difficulty in making a diagnosis from this one image. I would:

1. Make a wetmount of some of these lesions to see if any worms present (that will likely narrow down to nematode, cestode, digenean) or possibly spores (microsporidia or myxosporeans).

2. Also save some material for histology and if not an obvious eukaryote (or do this regardless, as there may be more than one thing happening here), then stain with H&E, Giemsa and Gram to see if bacteria associated with lesions.

I agree. One photograph is not possible to identify the pathogen. We can guess tentatively. Its may be caused by protozoa. You can initially observe the lesions under light microscope (40 X). Further, histology studies also will help you. 

Good luck 

In my opinion it may be one of 2 parasite infestation: Myxosporea or Trematoda (Didymozoata). Myxosporeans we can see under LM, but identification of these trematodes is very difficult.

Good luck, and I too hope you decide this interesting task.