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Case 189  - Discussion

Hematopathology Case

 

Lymphomatoid Granulomatosis of Lung

  • A rare extranodal EBV+B-cell lymphoproliferative disorder

  • Mostly involves lung, followed by skin (~50%) and less commonly liver, kidney, and CNS (~25% each)

  • Usually sparing of lymphoid tissues; uncommonly lymphadenopathy, splenomegaly and bone marrow involvement

  • Histopathology:

    • Mostly nodular mass lesions with angiocentric and angiodestructive

    • Background: polymorphic lymphoid infiltrate with mostly reactive T-cells, and plasma cells

    • Atypical larger B-cells: scattered or in small clusters; resemble lymphocytes, immunoblasts, and occasionally HRS cells; EBV+

    • Polymorphic cellular composition: predominantly lymphocytes and mixed plasma cells, immunoblasts, and scattered histiocytes

    • Usually no or rare neutrophils, eosinophils, well-formed granulomas, or reactive lymphoid follicles

    • Necrosis: common, infarct-like and coagulative, often centered on altered vessels with fibrinoid change, with nuclear debris but no neutrophils

    Grading:

    • Grade 1: polymorphic lymphoid infiltrate without cytologic atypia; absent or rare large transformed cells; necrosis usually focal; EBV+ cells < 5/HPF

    • Grade 2: occasional large transformed cells in a polymorphic background, maybe in small clusters; necrosis  more common; EBV+ cells 5-20/HPF

    • Grade 3: inflammatory background and frequent large atypical cells or in larger aggregates, often markedly pleomorphic and HRS-like cells; necrosis usually extensive; extremely numerous EBV+ cells >50/HPF or form small confluent sheets

    • A uniform population of large atypical EBV+ B cells without a polymorphic background should be classified as DLBCL and is beyond the spectrum of LYG

  • Immunophenotype

    • Mostly reactive small T cells, CD4+ > CD8+

    • EBER+ B-cells: positive for CD20, PAX5, and CD79a; may be CD30+; negative LMP-1 and CD15

  • Clonal IGH@ in most cases of grade 2 and 3