Ring Around the Roseys in Anal Sac Adenocarcinoma

Pseudoacinar structures (aka rosettes) are a type of cell pattern you may see in neuroendocrine (and neuroendocrine-like) neoplasms where the epithelial cells and their nuclei form little circles.

This is an FNA from an anal sac adenocarcinoma in a dog, a type of neoplasm in which pseudoacinar structures are very commonly seen!