a Several foamy looking histiocytes as well as multinucleated giant cells are present in and around a vein of a lymph node. H&E; bar = 50 µm. b Same vein as in A with positive (red) material in the cytoplasm of a multinucleated giant cell. Modified Ziehl–Neelsen; bar 50 µm. c Higher magnification of the multinucleated giant cell. Modified Ziehl–Neelsen.