Figure 1.

Representative pathologies observed in patients with HLH. Many patients with HLH revealed evidence of hemophagocytosis in the bone marrow (a–c, with arrows pointing to macrophages containing phagocytosed and degenerate intracellular cellular material). Acute tubular injury was frequently seen in autopsy kidneys; however, the more specific pattern of tubular injury exhibiting features of osmotic tubulopathy (radiocontrast-associated) was also observed (d). Less frequently encountered kidney pathologic findings included cortical coagulative necrosis (e, with necrotic tissue on the left and viable cortex to the right of the figure), disseminated and invasive Aspergillosis (f, with fungal organisms within the wall of an artery; f inset, organisms highlighted with a Grocott’s methenamine silver, GMS, stain), and in a sole case evidence of interstitial hemophagocytosis (g; g inset, immunoperoxidase staining for CD68 highlights interstitial macrophages containing phagocytosed cellular material). By electron microscopy, endothelial tubuloreticular inclusions were identified in patients with systemic lupus erythematosus with or without concomitant viral infection (h, arrows pointing to the endothelial tubuloreticular inclusions). Bone marrow aspirate smears were stained with Wright-Giemsa (a and b). Paraffin sections were stained with hematoxylin and eosin (c, e, f, and g), GMS (f inset), and periodic acid Schiff (d). Original magnifications for e at 200×; for d, f, and f inset at 400×; for a–c, g, and g inset at 600×; and for h at 40,000×. HLH, hemophagocytic lymphohistiocytosis.