Repair renal tubular cells: a potential false-positive diagnosis in urine cytology.

To study the cytopathology of repair renal tubular cells (RRTCs), the Papanicolaou-stained urine sediments of 371 patients with mild and moderate renal tubular injuries were reviewed. In 46 cases, the urine sediments showed, in addition to a mild or moderate increase in number of RTCs, a few isolated and clustered RRTCs that displayed well- or ill-defined, variably abundant, granular or vacuolated cytoplasm; slightly pleomorphic nuclei; and conspicuous or prominent nucleoli. A spectrum of nuclear changes ranging from mild to moderate atypias and/or severe atypia were present in many cases. These RRTCs stained strongly positively with vimentin antibody in 92.3% of the cases.