Thank you, cheekywhiskers, it's nice to have that reassurance from another vet. I made the mistake of spending half the weekend researching MCTs on line and of course found people with younger dogs that had MCTs. But his vet said the same thing you did, that in a younger dog it could be a histiocytoma. He's also half weimeraner and they're a breed at risk for MCT. I really should know better than to google crap like that. I had myself convinced before the surgery that all three of them would be MCTs since I'd read that having multiple is, of course, much worse than having one. The other two were under the skin so I couldn't compare them. So it was a relief to hear she thought the other two looked like benign cysts when they were removed.