Role of Expression of p63 and Calponin in Prostatic Biopsies

Abstract

Introduction: Histopathological diagnosis of benign prostatic hyperplasia and prostatic carcinoma may pose problems due to presence of mimickers. p63 is confined to basal cells/ myoepithelial cells of prostate and is absent in prostatic cancer. In prostate cancer there is presence of reactive stroma instead of normal fibro muscular stroma. Calponin is expressed in cytoplasm of smooth muscle cells of normal stroma and its decreased or loss of expression is believed to play a role in tumorigenesis. Aim: To assess the expression of p63, a nuclear marker and calponin, a cytoplasmic marker in prostatic lesions and the relationship between the immunostaining and histologic grade of prostatic carcinoma. Materials and Methods: Biopsy specimen from a total of 30 cases between ages 70-90 years which included 15 cases of Benign Prostatic Hyperplasia (BPH), 15 cases of prostatic carcinoma were obtained by Transurethral Resection of Prostate (TURP) and needle biopsies. For each case biochemical parameters were obtained. Immunohistochemical analysis was performed on routinely processed, formalin fixed, paraffin embedded tissue. Tissue sections were cut at 5 μm thickness and mounted on gelatin coated slides. Immunohistochemical staining was done for both p63 and calponin. Expression of each of markers was graded accordingly. Results: p63: Out of the 30 cases, 93% of BPH showed positive staining and 100% of prostatic carcinoma showed negative staining of which 8 cases showed cytoplasmic staining. Sensitivity was 93% and specificity was 100% respectively. Calponin: Out of the 30 cases, 100% BPH cases showed moderate to high staining index and 73% of prostatic carcinoma showed zero to low staining index. Sensitivity of calponin was 100% and specificity was 74%. Conclusion: p63 and calponin are highly expressed in benign and pre neoplastic lesions. p63 is a valuable tool with high specificity in differentiating BPH from prostatic carcinoma. The decreased or absent stromal staining of calponin which indicates a reactive stroma in malignancy can be used in conjunction with p63 for confirmation of diagnosis of prostatic carcinoma.

Keywords

• benign prostatic hyperplasia
• basal cells
• prostatic cancer
• tumourigenesis