PMC6442326_01
(a) Section from the tumor shows aggregates of lymphohistiocytic proliferation with numerous plasma cells separated by areas of fibrosis (H and E; x100). (b) Section from the tumor shows aggregates of foamy and vacuolated histiocytes. Some of the histiocytes engulf lymphocytes (emperipolesis) (H and E; x200). (c) Section from the tumor shows positive nuclear and cytoplasmic S100 immunostaining in the histiocytes (x200). (d) Section from the tumor shows positive CD138 immunostaining in the plasma cells surrounding blood vessels (x200). (e) Section from the tumor shows positive immunoglobulin G immunostaining in the plasma cells (x200). (f) Section from the tumor shows positive immunoglobulin G 4 immunostaining in the plasma cells, and the ratio of immunoglobulin G 4/immunoglobulin G is <5% (x200)
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F1
Microscopic examination revealed aggregates of histiocytes with abundant cytoplasm admixed with numerous plasma cells and some lymphocytes [Figure 1a and b]. Immunohistochemistry study revealed that the histiocytes were positive for CD68 and S100 [Figure 1c] and negative for CD1a and langerin. The plasma cells expressed CD79a, CD138 [Figure 1d] and appeared polyclonal with Kappa and Lambda light chain stains. The immunoglobulin G (IgG) 4/IgG ratio was <5% [Figure 1e and f], which against the diagnosis of IgG4-related disease.