Glomerular hemophagocytic macrophages in a patient with proteinuria and clinical and laboratory features of hemophagocytic lymphohistiocytosis (HLH)

Hemophagocytic lymphohistiocytosis (HLH) is a heterogeneous disorder characterized by excessive activation and proliferation of nonmalignant histiocytes, which are commonly found in bone marrow, lymph nodes, spleen and liver in affected patients. Here, we report the presence of glomerular macrophages, including one showing erythrophagocytosis, on renal biopsy in a 25-year-old patient with clinical presentation and laboratory changes consistent with HLH. The clinical course was marked by persistent fever for 2 months, pleural and pericardial effusion, splenomegaly, lymphadenopathy, pancytopenia, cardiac arrhythmias, multiple organ dysfunction, and proteinuria, with demise after a 2-month hospitalization. Positive assay for Epstein–Barr virus (EBV), marked hyperferritinemia, hypofibrinogenemia, hypertriglyceridemia, elevated anti-nuclear antibody, proteinuria, and decreased circulating NK cells by flow cytometry were compatible with the diagnosis of HLH. We suggest that the glomerular hemophagocytic macrophages, which have not heretofore been described in the kidney of a patient with HLH, may have contributed to renal dysfunction manifest as proteinuria.