Acute lymphadenitis

• Lymphadenitis is inflammation of lymph nodes
  

• • See nodal enlargement with edema, follicular hyperplasia, and germinal center proliferation

  • The follicular centers show lots of mitotic figures (virgin B cells undergoing lymphoid transformation), “tingible body macrophages” containing cellular debris (seen in cells eating Ag to present to differentiating B cells), and maybe necrotic abscess formation (acute necrotizing lymphadenitis)

  • Neutrophils may be seen around the follicles and within the sinuses, especially with abscess formation

  • Affected nodes become tender due to capsular distension (nodes will feel squishy and there will be local hyperemia if the process is from infection…this is not true with CA)

  • Draining sinuses may form with fungal infections…these drain necrotic node debris out onto the skin

  • Causes

    • Commonly seen in nodes draining areas of bacterial infection

    • Foreign body reactions

    • IV drug users may have lymphadenopathy in the limb they inject into (foreign bodies?)

    • Mesenteric lymphadenitis (may mimic acute appendicitis; from Yersinia enteritis)

    • Generalized lymphadenopathy seen with viremia, septicemia

Category: Medical Subject Notes , Pathology Notes