Immune-mediated polyarthritis in a cat

Ragocytes LE

In this direct smear of a joint fluid in cat with polyarthritis, there are numerous neutrophils containing purple to dark blue particulate material in their cytoplasm (presumably nuclear fragments or nuclear antigen:antibody complexes) (arrows). These cells are called “ragocytes”. Some classic lupus erythematosis (LE) cells are also seen. The latter are neutrophils which contain large light purple homogenous nuclear material in their cytoplasm (displacing nuclei to the periphery) (arrowheads).