Abstract
A 45-year-old man with a low titer of hepatitis B virus (HBV) was diagnosed with nephrotic syndrome. A subsequent test for human immunodeficiency virus (HIV) was positive. Kidney biopsy revealed some signs of collapsing variant of focal segmental glomerulosclerosis (FSGS), but the predominant finding was a cellular variant of FSGS. Two years after receiving tenofovir, urine protein became negative, and the patient was finally diagnosed with HIV-associated nephropathy. Collapsing variant of FSGS is considered typical of HIV-related nephropathy, but the cellular variant of FSGS in this patient represents another type. The cause of many FSGSs is often never identified, making cause-based treatment difficult. This case demonstrates that identification of the cause of FSGS can lead to treatment of FSGS.