What type of inflammation is primarily seen in Reactive Arthritis?

Reactive arthritis is characterized by non-granulomatous inflammation. This type of inflammation typically occurs as a response to an infection or an insult elsewhere in the body rather than being primarily caused by the presence of a pathogen in the joints themselves. It is often associated with preceding infections, particularly urogenital or gastrointestinal infections, which trigger an autoimmune response leading to joint inflammation.

Non-granulomatous inflammation features a more fluid exudate, lymphocyte infiltration, and often presents without the formation of granulomas, which are clusters of immune cells that typically develop in response to chronic inflammation or specific pathogens. Reactive arthritis primarily involves synovial fluid changes and the infiltration of leukocytes, particularly neutrophils and lymphocytes, leading to the inflammation of the joints without forming granulomas.

In contrast, granulomatous inflammation is marked by the formation of granulomas, which are not the typical response in reactive arthritis. Types like serous inflammation are characterized by a clear exudate and occur in different inflammatory contexts. Purulent inflammation involves the presence of pus, which is not the predominant feature of reactive arthritis either. Thus, recognizing the unique inflammatory processes in conditions like reactive arthritis helps in understanding its pathogenesis and guiding clinical management.