Hemophagocytic Syndrome With Histiocytic Glomerulopathy and Intraglomerular Hemophagocytosis.

Hemophagocytic syndrome (HPS), a rare and life-threatening disease, is characterized by hyperactivation of the immune system that causes hypercytokinemia and potential multiorgan failure. Acute kidney injury is the most common kidney manifestation of HPS and is generally considered a poor prognostic factor. Glomerular involvement is uncommon and usually manifests as either podocytopathy with collapsing glomerulopathy or thrombotic microangiopathy. We report a rare case of severe histiocytic glomerulopathy in a patient with HPS who presented with acute kidney injury and proteinuria. Kidney biopsy revealed massive glomerular infiltration by macrophages resembling proliferative glomerulonephritis accompanied by intraglomerular hemophagocytosis and mild features of glomerular thrombotic microangiopathy. The patient's kidney failure and proteinuria responded rapidly to high-dose pulse methylprednisolone followed by a tapering course of oral prednisone. Our case expands the renal pathologic spectrum of HPS to include histiocyte-rich glomerular infiltration and intraglomerular hemophagocytosis. Greater awareness of this entity is needed to ensure prompt recognition and appropriate therapy.