A Rare Nephrotic Syndrome Related to Chronic Lymphocytic Leukemia: Focal Segmental Glomerulosclerosis.

Chronic lymphocytic leukemia (CLL) is a hematological disease characterized by the proliferation of monoclonal B-lymphocytes. Although autoimmune complications such as autoimmune hemolytic anemia and immune thrombocytopenia are common in CLL patients, nonhematological autoimmune complications are rather rare. The most common renal involvements are membranoproliferative glomerulonephritis and minimal change disease. Focal segmental glomerulosclerosis (FSGS) is predominantly associated with Hodgkin's lymphoma among hematological malignancies. FSGS associated with CLL is rarely reported in the literature, with a poor understanding of the common pathophysiology and a very limited experience with this co-occurrence. Although Rai Stage 1/Binet Stage B CLL, our 61-year-old case, who was diagnosed with secondary FSGS, which is a very rare complication, was treated with fludarabine, cyclophosphamide, and rituximab (FCR) combination. Following the treatment, a complete response was achieved about CLL, and the patient, whose renal findings recovered, is in remission and under follow-up for six years. Although the mechanisms between CLL and autoimmune complications are not fully elucidated, it is usually related to immune disorders like an abnormal T-cell response and polyclonal antibody production. While FSGS is very rare in lymphoma, its co-existence with CLL is reported only in a limited number of case reports. Steroids may be used in these patients; however, in cases not responding to steroids, treatment of the underlying CLL is required.