CSH in the bone marrow and the liver.

(A,B) Initial bone marrow biopsy. (A) Bone marrow shows a diffuse infiltrate of histiocytes stuffed with crystalloid inclusions (Giemsa, × 1600). (B) Plasma cells (marked by arrows) are only rarely admixed (Giemsa, × 4000). (C-F) Immunohistochemistry reveals positive reactivity of the histiocytes not only for IgA (C) and κ (D), but also for IgG (E) and λ (F; × 1000 each). (G-I) Bone marrow at the time of autopsy. (G) Plasma cells are multiplied compared to the initial biopsies and stain immunohistochemically positively for a monoclonal plasma cell marker (× 1600). (H) Immunohistochemistry for κ light chains reveals positive reactivity in histiocytes and in plasma cells (marked by arrows). Plasma cells stain less intensely possibly due to the conformation of the produced κ light chain (× 4000). (I) They also stain positively for IgA heavy chain (× 4000). (J,K) Liver biopsy 5 months before death. (J) Swollen Kupffer cells obstruct sinusoidal spaces (H-E; × 1200). (K) The Kupffer cells are highlighted immunohistochemically by their expression of CD68 (× 2500).