Abstract
A 28-year-old male with a 10-year history of asymptomatic proteinuria received renal biopsy because of recently developed nephrotic syndrome and of impairment of renal function. Laboratory examinations revealed urinary protein of 5-7 g/day, total protein of 5.4 g/dl and glomerular filtration rate of 49 ml/min. In urinary sediments, oval fat bodies and cholesterol crystals were observed. Light and immunofluorescence microscopies revealed moderate mesangial proliferation and mesangium-dominant IgA deposits in association with small crescent formation in glomeruli. In addition, in the tubular lumens, especially in the corticomedullary junction, spindle or needle-shaped cholesterol crystals were observed. By electron microscopy, small crystals were found in the tubular epithelial cells as well as in the tubular lumens. Some of the latter were large enough to compress the epithelial cells and tubular basement membrane and grew out into the interstitium to form granulomas by infiltration of mononuclear cells surrounding the crystals (cholesterol granuloma). Of 258 patients with a histologically proven primary or secondary nephrotic syndrome, similar cholesterol crystals were observed in 7 patients (2.7%), two with membranous nephropathy, two with membranoproliferative glomerulonephritis and 3 with IgA nephropathy. However, the crystals were not found in 82 patients with minimal change nephrotic syndrome, in which nephrotic syndrome does not generally persist for a long time. The granulomas were observed in the 3 patients (1.2%) with IgA nephropathy. Six of the 7 patients described above showed an elevation of serum cholesterol level at the time of renal biopsy or during the nephrotic phase before biopsy. These results suggest that both choresterol crystals and granulomas may be formed in a circumstance of hypercholesterolemia, increased permeability of glomerular capillary wall and persistence of nephrotic syndrome, and to our knowledge, this case report is the first description of a patient showing cholesterol crystals and granulomas in renal tubules and interstitium in the Japanese literature.
