How can you tell if a mass is due to vaccine hypersensitivity?
It always makes me happy when I can be the bearer of good news. Not everything that is pretty in the path world is terrible! π
This 10 year old pupper presented to his vet for development of a subcutaneous swelling in his lateral thoracic area.
The FNA shows mixed lymphocytic and histiocytic inflammation which is non-specific.
BUT. The kicker is all that magenta globby goo! That stuff is being eaten up by macs. What is that you ask?
Vaccine adjuvant!
Adjuvant often stains this bright magenta color (yes, even with Diff Quik). So, when we see this in an FNA from a mass in a sus area, we can deduce that it's adjuvant.
Unsurprisingly, this pup was vaccinated 2 weeks ago which is the typical timeline for these delayed vaccine reactions to occur (often 1-2 weeks later or so).
So, no bad news for this dog today! Woohoo!
