3-month-old Belgian malinois with lump on Ischiatic tuberosity bka butt

Hello everyone. I'm going to try to show you the best pictures I can. Please excuse the picture that has the powder on there because when I was putting a little on him he was so excited he jumped up and knocked it out of my hand. This is Phoenix born March 21st 2024 he is a Belgian malinois and I am embarrassed to say that when I got him I didn't think of putting a bed in his crate. With that being said that means even when he goes outside and sits on the porch that is also a hard surface. It did take him a long time to explore and get off the porch. He had no sign of trauma or bug bites or anything like that. The lump was kind of squishy like watery like a water balloon. When drained it did come out the watery blood twice when they ( vet ) drained it a week apart and also it had no infection smell. It was called a hematoma. But my thing is when I took him to get it drained for that second time the vet actually said which was a different Vet said it was located right on his bones. With that being said wouldn't it be considered as a hygroma -repeat it trauma due to sitting or sleeping on hard surface, located on bony points on his butt cheeks. He sleeps on his back a lot. As I was looking through the old pictures which your seeing now I noticed that the right side was just not as swollen but it was swollen. Now how it feels is the left one started shrinking but now it has kind of hardened like a rock in any kind of funny shape but the right side still swollen but not as bad as the left one was. Feel free to ask me more questions. And yes the first time they drained it and I told them about him sleeping on hard floors and no bed in his crate they suggested me to get a bed and I got one that same day. ( I do try my best to do what's right and what I'm asked of) So could this possibly be a hygroma and not hematoma? The picture with the Earth dust is the one where I seen the one on the left side but I didn't even realize until I looked really good that there was actually two one on each side. 

Hello -  and thankyou for sharing this interesting case.  You say that they drained it - was this to such an extent that they are absolutely adament that everything is normal /  there is no extra testicle or abnormality to the bone underneath?  Have they spun the stuff down to see what % blood cells it actually contains?  Heamatomas are full of blood, so should be obvious.  Cysts and hydramoas are frequently clear. Does an ultrasound scan weild anything?  This strikes me as an unusual presentation for a haematoma or a hygroma (the latter are usually associated with the caudal elbows and form where bone hits a hard surface) or a cyst.   I feel that a good move would be for the vet to speak to their existing pathology lab.  Pathologists are interesting people, not least because they get to see the 'once-in-a-lifetime interesting' tissues from every vets.  So when something is rare or unexpected, they might have seen one before.  I have been sweeping my mind for other possibilities; a tumour, an encysted tumour, a malformed testicle in a slightly strange place,  the blood vessels associated with such an event, a hernia.....  but having not examined the lump or case, I am in a poorer position to have an opinion on either what it is, or how to confirm that, than your own vet who has examined the patient.   My experience of pathologists (most vets will use one) is that they love it when a vet calls them up to ask their opinion on the best plan for sampling an unusual lump.