The malignant potential of nephrogenic adenoma is still a matter of controversy and therapeutic regimens of this morphologic entity range from partial, even total cystectomy to watchful waiting. The objective of the current study was to evaluate several robust image cytometry-DNA histogram classifiers and to search among those for factors that separate a biologically nonaggressive metaplastic lesion from lesions with increased malignant potential.
The study included bladder irrigation specimens, 23 preceding transurethral resection of nephrogenic adenoma and 24 preceding resection of papillary bladder carcinoma. Feulgen-stained nuclei were imported to a static image analysis system, and densitometric data were interpreted by two different software programs. Histograms were described numerically by DNA index, 2c deviation index, and by 5c/9c-exceeding and euploid polyploidy rates. In addition, an interpretation algorithm based on a dual parameter analysis with an integrated automatic threshold was used.
The numeric classification of DNA histograms of patients suffering from nephrogenic adenoma resulted in DNA indices between 0.91 and 1.15. The 2c deviation indices ranged from 0.03 to 0.43, and the 5c exceeding rates ranged from 0.0 to 1.58. None of the measurements showed nuclei exceeding 9c. The p25-75 ranges of 2c deviation indices in nephrogenic adenoma and papillary urothelial carcinoma did not overlap. These findings might be explained by minor proliferative activity in nephrogenic adenoma. Euploid polyploidy rates less than 5% confirm this explanation. Risk analysis documented high risk only for those patients with nephrogenic adenomas who had proven transitional cell carcinoma in their history.
DNA estimation by image cytometry of urinary bladder irrigation specimens appears able to separate papillary bladder lesions. The method detects those lesions with higher malignant potential but is limited in separating entities with low malignant potential. Comparison of the discriminative power of robust numeric DNA classifiers reveals the 2c deviation index superior to the widely used DNA index and the 5c exceeding rate in this material.