Pseudomyxoma Ovariilike Posttherapeutic Alteration in Prostatic Adenocarcinoma

Abstract

Neoadjuvant combination endocrine therapy that uses leuprolide and flutamide may result in various histologic changes in nontumoral and cancerous prostatic tissues. Posttreatment pseudomyxoma ovariilike change in prostatic adenocarcinoma is a distinctive alteration that may be the only evidence of regressed tumor and can be potentially confused with mucinous carcinoma. We studied 53 clinically localized prostatic adenocarcinomas after 3 to 5 months of treatment with leuprolide and flutamide. Alterations in prostatic adenocarcinoma in posttreatment radical prostatectomy specimens were assessed and compared with pretreatment needle biopsies. All radical prostatectomy specimens exhibited previously well-characterized therapy-associated changes in benign and malignant elements. Thirteen (20%) cases exhibited a distinctive alteration not seen in pretreatment needle biopsies that consisted of minute to large pools of extravasated secretions that resembled pseudomyxoma ovarii and that dissected through prostatic stroma with an infiltrative appearance when viewed at low power. Associated recognizable tumor was present in 10 of 13 (77%) of these cases. Secretions were basophilic in routine sections and contained occasional degenerated cells. Rare pancytokeratin positive cells were seen at the secretion/stroma interface with uniformly negative staining for the high molecular weight keratin 34 beta E-12. The secretions were periodic acid-Schiff positive after diastase digestion and were mucicarminophilic and reactive with Alcian blue at a pH of 2.5. These foci comprised < 5% of the tumor in 5 cases and 5-40% in 5 cases. In 3 cases, 1-2 foci < 1.0 mm exhibited the pseudomyxoma ovariilike changes and were the only evidence of treated tumor. There was no correlation between the presence of pseudomyxomalike change and dose/duration of neoadjuvant therapy, postprostatectomy clinical follow-up, original or final Gleason pattern/score, or pathologic stage. Pseudomyxoma ovariilike change consists of extravasated acid mucin, lacks prostatic basal cells, often occurs in intimate association with residual prostatic adenocarcinoma in posttreatment radical prostatectomy specimens, and probably represents tumor regression as a result of tumor cell attrition secondary to androgen ablation.