Abstract
Objective: We studied cytological features and the origin of oval fat bodies (OFBs) in voided urine, and discus their diagnostic and clinical significance.
Study Design: We studied 31 patients with nephrotic syndrome who showed OFBs in voided urine. OFBs in 15 were examined immunohistochemically to determine origin. Renal biopsy was done in 16 to determine the relationship between renal histology. OFBs, and clinical course.
Results: OFBs were found as cell clusters or individual cells. Papillary clusters with nuclear overlapping and dark nuclear staining were occasionally observed. Clustered OFBs were positive for cytokeratin and CD15, and negative for EMA. Dispersed OFBs were positive for CD68 and negative for cytokeratin. Histological examination showed that interstitial fibrosis, tubular atrophy, and interstitial CD68 positive cells were more frequently found in OFB-positive cases than in control (p<0.05). Progression to chronic renal failure was only found in OFB-positive cases.
Conclusion: Our results suggest that OFBs may originate in both proximal tubular cells and macrophages. OFBs reflect tubulointerstitial changes and can be a predictor of nephrotic syndrome progression. It should be kept in mind that OFBs in clusters showed occasional atypia in urinary cytology.
