A Rare Cause of Collapsing FSGS: Hemophagocytic Lymphohistiocytosis-Associated with Epstein-Barr Virus

Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a severe, life-threating syndrome of pathologic immune system activation. Viral infection, such as Epstein Bar Virus (EBV) infection, is a known trigger of HLH. Collapsing focal segmental glomerulosclerosis (FSGS), an aggressive variant of FSGS, that may be idiopathic or occur with infectious or inflammatory conditions. Here we present a case of a patient who presented with AKI (acute kidney injury) requiring hemodialysis who was later diagnosed with HLH associated EBV and collapsing FSGS/ATN on renal biopsy. Case Description: A 42-year-old Somalian male with hypertension and new diagnosis of ESRD presented to the emergency department for hemodialysis (HD). He had presented two weeks prior at an outside hospital with renal failure ultimately thought to be ESRD from hypertension as his serologies were negative and ultrasound did not show obstruction. He had no prior baseline renal function as he did not follow routinely with primary care. During HD, he was found to be tachycardic and febrile, requiring admission. He underwent extensive workup for infectious etiologies and was ultimately diagnosed with HLH associated EBV. Genetic HLH panel was negative. He also underwent renal biopsy during this admission with evidence of FSGS with collapsing features and extensive ATN. He was started on rituximab and dexamethasone with improving results in his EBV titers from 21,000 to 10,000 after dose #4 and was discharged in stable condition. He remained on hemodialysis without evidence of renal recovery. Unfortunately, he presented a month later and was found to be hypotensive, febrile and tachycardic on dialysis. There was evidence of relapse with EBV PCR >110,000 and ferritin >40,000. He was also found to have disseminated cryptococcal infection, encephalopathy, and shock requiring multiple pressors and CRRT and eventually passed during admission. Discussion: Collapsing FSGS may be idiopathic or occur with infectious or inflammatory conditions. HLH secondary to EBV infectious resulting in collapsing FSGS is rare and the exact mechanism is unknown. This case highlights the important association between HLH associated EBV, and collapsing FSGS in a rapidly progressive course leading to ESRD as well as the need for thorough evaluation of patients with presumed hypertensive kidney disease