Immunohistochemical assays in prostatic biopsies processed in Bouin's fixative

Abstract

Aims: To investigate the problems involved in undertaking immunohistochemistry (IHC) and nuclear morphometry using Bouin's fixed prostate biopsies.

Methods: Archival Bouin's fixed and formalin fixed, paraffin wax embedded prostatic biopsies were immunostained for three nuclear biomarkers (minichromosome maintenance protein 2 (MCM-2), p27, and Ki-67), one membrane localised biomarker (C-erb-B2), CD34, and alpha methylacyl-CoA racemase (AMACR). The quality of IHC staining was compared between tissues prepared separately in both fixatives. Feulgen staining was also performed on Bouin's fixed tissues to check its suitability for nuclear morphometry.

Results: MCM-2 staining was completely negative in Bouin's fixed tissues, whereas p27 showed more background and excess cytoplasmic staining in Bouin's fixed versus formalin fixed tissues. C-erb-B2 showed non-specific, strong luminal cell staining in the Bouin's fixed tissue. Feulgen staining was also very weak in Bouin's fixed tissue. However, Ki-67, AMACR, and CD34 worked equally well in Bouin's and formalin fixed tissues.

Conclusions: Bouin's fixed tissues may be unsuitable when subsequent IHC and morphometry are contemplated. An awareness of which antibodies are suitable for use in Bouin's fixed biopsies is essential.

Figure 1

(A) Bouin’s fixed (BF) prostate biopsy stained for MCM2 showing no reactivity. (B) The corresponding formalin fixed biopsy shows strong immunoreactivity, predominantly in the basal cell compartment. (C) BF prostate biopsy stained for p27 shows weak nuclear staining with abundant cytoplasmic positivity, whereas the formalin fixed biopsy (D) shows strong nuclear positivity with very weak cytoplasmic staining.