Definition time: Panniculitis
Panniculitis can be caused by a number of things including: trauma, foreign bodies, infectious organisms, pancreatic disease, Vitamin E deficiency, adverse drug reactions, immune mediated disease, and idiopathic.
This photo is an example of panniculitis caused by a vaccine hypersensitivity reaction!
Here we can see a combination of macrophages, neutrophils, small lymphocytes, and a rare eosinophil. Also, if you look closely, you can see magenta adjuvant in the cytoplasm of one of the macrophages. Can you find it? (Hint, it’s at 12 o’clock)