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Case 7 - Discussion

Hematopathology Case

Immunostains of the paracortical expanded area:









This is a beautiful, textbook case I had recently. Patient was a young female with fever, superficial lymphadenopathy and negative serology tests. Histologically, the lymph node had mostly preserved architecture and showed multiple irregular, patchy paracortical expansions of lymphocyte and histiocytes without follicular hyperplasia. The paracortical expansion contained a mixture of: 1). histiocytes, with frequent C-shaped forms and expression of MPO; 2). T-cells, mostly CD8+ cells; 3). plasmacytoid dendritic cells, not very obvious in this case and CD123 staining did not work well; and 4). abundant karyorrhectic debris. No neutrophils or plasma cells were noted. B-cells were essentially absent in the center of the expanded areas and were rarely present at the periphery. Overall, the morphologic features are typical for "histiocytic necrotizing lymphadenitis", proliferative stage.

Kikuchi-Fujimoto Lymphadenitis

§     Also called “histiocytic necrotizing lymphadenitis”

§     Typically young Asian women, most lack antinuclear antibodies

§     Often unilateral cervical lymphadenopathy, fever and leukopenia

§     Usually resolves spontaneously within several months

§     Proliferative Stage:

o    Paracortical, patchy proliferation of medium to large lymphoid cells, histiocytes, and plasmacytoid dendritic cells

o    Histiocytes with irregular nuclear and bland chromatin

o    Plasmacytoid dendritic cells tend to cluster

o    Neutrophils, eosinophils, plasma cells rare

§     Necrotic stage:

o    Patchy necrosis in paracortex, focal to extensive geographic, mostly irregular

o    Abundant karyorrhectic debris in the center of necrosis

o    Mixed immunoblasts, crescentic histiocytes and plasmacytoid dendritic cells

o    Lack of neutrophils and plasma cells

§     Resolution stage:

o    Large number of foamy macrophages

§     IHC:

o    T cells: abundant, CD8+ > CD4+

o    Histiocytes: CD68+ and MPO+

o    Plasmacytoid dendritic cells, CD68+, CD4+, CD43+, CD123+, CD56-

o    Rare B cells

§     May be associated with SLE

§     DDX: Lupus lymphadenitis - extensive necrosis, hematoxylin bodies, and plasma cells or neutrophils