lymph node



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  • Normal

    • capsule
    • subcapsular sinus
    • cortex
      • primary follicle: mature B cells
      • secondary follicle: has germinal center, mantle zone, and FDCs
      • mantle zone: primary follicle cells around a GC
      • germinal center: class switch IgM/D -> IgG/A/E
        • light zone: centrocytes, FDCs
        • dark zone: centroblasts
      • marginal zone
        • more prominent in spleen, mesenteric nodes
        • surrounds follicles
        • naive and memory B cells
        • resemble centrocytes
    • paracortex: interfollicular zone, T cells, T-APCs (interdigitating dendritic cells)
      • immunoblasts: prominent single nucleoli
      • plasmacytoid dendritic cells: apoptotic debris
    • medulla: B cells, T cells, plasma cells, macrophages, dendritic cells
    • sinus: histiocytes, monocytoid B cells beneath sinus

  • Immunophenotype

    • mature B cells: IgM, IgD, CD21, CD23
    • germinal centers: BCL2-, BCL6+, CD10+
    • mantle zone: IgD+, BCL2+, BCL6-

  • Follicular

  • Sheets of lymphs

  • Histiocytic

  • Necrosis

    • HSV, get AFB, GMS (mycobacteria, fungus)
    • PCP (foamy necrosis)
    • lupus (pure necrosis w/o eos, PMNs, or granulomas)
    • Kikuchi disease
    • infarct (rim sparing)

  • Vascular

    • thin wall: bacillary angiomatosis, Kaposi, vascular transformation of sinuses
    • thick wall: Castleman, AITL, HIV
    • pleomorphic: angiosarcoma

  • Other

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