Stereological estimates of nuclear volume correlated with histopathological grading and prognosis of bladder tumour

Summary

The aim of this retrospective study is to provide morphometric data which make grading of urinary bladder tumours objective and reproducible by stereological estimation of nuclear volume using the principle of estimating of the volume of particles of arbitrary shape. The study includes 92 specimens: 12 from normal bladder mucosa, and 80 from bladder tumours (15 grade I, 45 grade II, 19 grade III and one grade IV according to Bergkvist et al. 1965).

After standard fixation, embedding, sectioning and hematoxylin-eosin staining, an unbiased estimate of the mean volume of nuclei sampled with a change proportional to the volume:$\bar v_V = \frac{\pi }{3} \cdot \overline {l_0^3 }$ was calculated. Here l₀ is the length of the intercept through a test point hitting a nucleus measured in a random direction through the test point.

The weighted means of nuclear volume in bladder tumours are spead over a wide range and show a strong correlation with the Bergkvist grade. Moreover, the relationship between the weighted mean volume of nuclei in bladder tumours and the prognosis is very good. Only one of 35 patients with a mean nuclear volume below 300 μm³ died of bladder cancer whereas 18 of 19 patients with a mean nuclear volume above 500 μm³ developed invasives tumours or died of their disease. This simple and fast estimate of nuclear volume seems to provide objective data of high prognostic value.