Atypical nephrogenic metaplasia of the urinary tract - A precursor lesion?

BACKGROUND, Nephrogenic metaplasia with cytologic atypia (atypical nephroge nic metaplasia) is occasionally encountered and its biologic potential is u ncertain. METHODS. The authors describe 18 cases of atypical nephrogenic metaplasia c haracterized by the presence of prominent cytologic atypia, including nucle ar enlargement, nuclear hyperchromasia, and enlarged nucleoli. DNA ploidy a nalysis by digital image analysis and immunostaining for high-molecular-wei ght cytokeratin (34 beta E12), cytokeratin 7, cytokeratin 20, carcinoembryo nic antigen (CEA), epithelial membrane antigen (EMA), p53, and MIB-1 were p erformed in 9 cases. RESULTS. The mean patient age was 62 years (median, 65 years; range, 39-84 years). The male-to-female ratio was 2.6:1. Two patients had a history of n oninvasive papillary urothelial carcinoma. The typical clinical presentatio n was hematuria (8 patients) and voiding symptoms (5 patients). Cystoscopic findings were suspicious for neoplasm in 7 of 13 cases. The neoplastic cel ls were positive for high-molecular-weight cytokeratin, cytokeratin 7, and EMA, and were usually negative for cytokeratin 20 and CEA. p53 nuclear accu mulation and increased MIB-1 labeling index were seen in 4 cases. DNA ploid y analysis showed aneuploid pattern in 2 of 9 cases. The mean patient follo w-up was 3.5 years (range, 0.5-10.6 years); 2 patients had recurrent nephro genic metaplasia, and the remainder were alive without recurrence or urothe lial carcinoma. CONCLUSIONS. Atypical nephrogenic metaplasia is benign; it occasionally dis plays substantial cytologic abnormalities of no apparent clinical significa nce. Awareness of the spectrum of cytologic changes within this entity is c ritical to prevent overdiagnosis of cancer and avoid unnecessary treatment. There is no direct evidence that links atypical nephrogenic metaplasia to cancer. (C) 2000 American Cancer Society.