Traditional Serrated Adenoma
Microscopically, traditional serrated adenomas (TSA) have a villiform architecture and may be mistaken for tubulovillous or villous adenomas. The crypts are lined by tall columnar cells with abundant mucin-depleted eosinophilic cytoplasm. The nuclei are hyperchromatic and elongated with minimal cytologic atypia. Mitotic activity is low. One of the characteristic features is the presence of ectopic crypts (arrows).
Image courtesy of: American Registry of Pathology Press (@ARP_Press); Used with permission.