Clinical and immunological findings. (A) Absolute platelet numbers and hemoglobin levels over time (from acute phase until the present time). (B) FDG-PET showing hepatosplenomegaly and extensive mesenteric fat infiltration. (C) CD4/CD8 double-stained omental biopsy specimen (original magnification ×40), with CD4⁺ lymphocytes stained brown and CD8⁺ lymphocytes stained red, infiltrating between the mature adipocytes. (D) Hematoxylin and eosin–stained bone marrow biopsy specimen (original magnification ×40), showing trilineage hematopoiesis and scattered histiocytic cells with packed erythrocytes in the cytoplasm. Inset in the left bottom corner is Giemsa-stained bone marrow aspirate (original magnification ×100), highlighting a hemophagocytic histiocyte. (E) NK-cell function before (left) and after (right) treatment. (F) Absolute B-cell, T-cell, and NK-cell counts over time (from acute phase until the present time). Green shading indicates age-dependent normal values.