Figure 4

Illustration of hemophagocytosis and the most prominent extrahematologic features of Griscelli and Chédiak-Higashi syndromes. A, Hemophagocytosis in the bone marrow of a patient with familial hemophagocytic lymphohistiocytosis; arrow indicates an activated macrophage that has ingested several red blood cells. B, Partial view of the head of a child with Griscelli syndrome 2, shown to emphasize the ashengrey colour of hair. Electron microscopy images of a normal hair (left panel) and a hair of a person with Griscelli syndrome (right panel) are shown below; arrows indicate clumps of melanin specific for this disease. A defect in any of the proteins (myosin Va, RAB27A, or melanophilin) leads to identical pigmentary dilution in the three forms of Griscelli syndrome and their mouse models. C, Blood smear taken from a patient with Chédiak-Higashi syndrome. Arrows indicate large granules present in all cell lineages that orient the diagnosis toward Chédiak-Higashi syndrome.