Optimized preembedding method improves the histologic yield of prostatic core needle biopsies

The aim of this study was to optimize the core shape of prostatic core needle biopsies using a novel preembedding method, and to investigate the influence of the number of cores per tissue block on the histologic yield per section level.

Twenty-four core needle biopsies were taken from a fresh prostatectomy specimen, using an 18-gauge needle. Twelve core needle biopsies were conventionally fixed floating free in formalin-filled containers, whereas 12 biopsies were stretched between two nylon meshes, and placed in tissue cassettes before fixation. The total number of tissue sections per paraffin block necessary for complete workup of the tissue was determined. Using image analysis, the relation of the area of every fifth section level was calculated in relation to the total projected area of the biopsies. Both methods of tissue processing were compared for both parameters.

In contrast to the curved biopsies after conventional processing, the optimized preembedding method generally led to stretched cores after fixation and embedding. This method led to a 100% decrease in total number of tissue sections necessary for complete workup and to higher percentages of the tissue amount per section level compared to the total projected core area. These parameters were also influenced by the number of cores per paraffin block, but to a minor degree.

This study shows that optimized preembedding of prostatic needle biopsies improves the histologic yield per section level. The continuous occurrence of representative sections could improve diagnostic accuracy in the histological examination of prostatic core needle biopsies.