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

    • follicular lymphoma
    • follicular hyperplasia
      • infection: bacteria, protozoa, HIV
      • toxoplasma
      • HIV lymphadenopathy
      • Kimura disease
      • progressive transformation of germinal centers
      • nonspecific follicular hyperplasia
      • rheumatoid (starry sky)
      • Castleman disease
    • progressive transformation of germinal centers

  • Sheets of lymphs

    • lymphoma (monotypic or RS cells)
    • paracortical hyperplasia (polytypic): viral, drug
      • mono
      • HSV
      • CMV
      • drug related lymphadenopathy
      • nonspecific paracortical hyperplasia

  • Histiocytic

    • granuloma (get AFB, GMS)
      • mycobacteria, fungus, LGV, catscratch
      • other infections: Whipple, cryptococcus, leishmania
      • cat scratch disease
      • sarcoidosis
    • no granuloma (get GMS)
      • infection: fungus, toxoplasma, Whipple
      • dermatopathic lymphadenitis
      • LCH and histiocytic/dendritic neoplasms
      • Kikuchi
      • sinus hyperplasia
      • Rosai Dorfman disease

  • Necrosis

    • HSV, get AFB, GMS (mycobacteria, fungus)
    • PCP (foamy necrosis)
    • lupus (pure necrosis w/o eos, PMNs, or granulomas)
    • Kikuchi disease
    • infarct (rim sparing)
      • histiocytic necrotizing lymphadenitis
      • infections
        • cat scratch disease
        • CMV
        • HSV

  • Vascular

    • thin wall
      • bacillary angiomatosis
      • Kaposi sarcoma
      • vascular transformation of sinuses
    • thick wall
    • pleomorphic: angiosarcoma

  • Other

    • eos: Hodgkin, drug, filaria, Kimura
    • plasma cells: syphilis, Castleman, IgG4
    • lollipop GCs: Castleman
    • inflammatory pseudotumor
    • foreign body deposition
    • metastasis vs benign inclusions (nevus, glands)
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