Caught by Surprise - Microfilaria in Renal Biopsies

Microfilarial parasites can obstruct the lymphatic tree giving rise to varying lymphatic and extra-lymphatic symptoms. Renal manifestations can range from asymptomatic proteinuria, chyluria, and nephrotic syndrome, to acute glomerulonephritis. The diagnosis of filariasis is usually made by the demonstration of the parasite in the peripheral blood smear, with or without eosinophilia. The renal involvement by this parasite has been sparsely reported in the literature. We hereby report five cases of filariasis detected on histopathological examination of renal biopsies, performed for other indications, along with a brief report of the additional histological findings. Three native and two graft biopsies were included. All our patients were male, with a mean age of 47 years (range 37 to 66 years). The serum creatinine ranged from 1.2 to 12.9 mg/dL. The mean 24-hour urinary protein was 3.6 gm/day. Peripheral blood eosinophilia was not recorded in any case, however, ESR was raised in all cases. Urine examination revealed varying proteinuria, with hematuria in two cases. Histological examination revealed microfilaria in all five biopsies, along with focal segmental glomerulosclerosis in two cases, combined cellular and humoral rejection, minimal change disease and acute tubular necrosis in one case each respectively. All patients were treated with diethylcarbamazine 6mg/kg/day or 12 days, in addition to the renal medications. Diagnosing the parasite is crucial as the patient is likely to benefit due to the timely treatment of the disease. Reporting this case series highlights an interesting finding in nephropathology.