this look suspiciously similar to the hydatid cyst of Echinococcus granulosus....

May be an uncommon location: http://www.ncbi.nlm.nih.gov/pubmed/14616207 

http://www.cfsph.iastate.edu/DiseaseInfo/ImageDB/ECH/ECH_002.jpg

http://epivet.blogspot.com/2007/02/what-i-did-in-uganda.html

was it attached to the feutus, placenta or floating in between?

Thank you very much Maurizio, I think your suggestion is right, but how could we confirm this opinion? We have the content of this cyst, also the serum of the dam. 

Dear Dr Attaai, 

We found it free in the uterus after fetal manipulation and removal. May be it was attached anywhere, because the blood vessels was still clear and visible, this may be means it was attached with the general circulation.   

not a specialist, better talk with your diagnostic department but conclusive should be the detection of protoscolex in the cyst fluid, evidence of an antigen effect of the fluid (Casoni test) etc   

I do not think that it is the hydatid cyst because the presence of the vasculature on its surface. 

Looks like a chorionic vesicle or a type of hippomanes to me.

Hippomanes are said to be quite frequent in camelids, and would be nothing to worry about.

Cystecircus ?

I think it is a remnants of primary yolk sac (exocoelomic cyst).

Dear Colleagues

After discussion with Professor H. M. Omer (Prof. of Parasitology) and after microscopic examination of the vesicle content, he suggested that the case is Cysticercus tenuicollis.

Ali

May I suggest that you confirm the diagnosis by PCR.

If it is confirmed, I think this could make an interesting publication.