Tertiary Lymphoid Structure

**Semantic type:** Finding

**Definition:** Ectopic lymphoid formations in nonlymphoid tissues. They resemble lymph nodes and can contain B-cell-rich follicles with germinal centers, T-cell-rich interfollicular areas, and high endothelial venules. Causes include persistent infections, autoimmune disorders, and cancer.

**Synonyms:** - TERTIARY LYMPHOID STRUCTURES - TLS - TLS