To the Editor: Paner et al reported a very interesting series of prostatic giant cystic tumors including 3 giant cystadenocarcinomas and 1 giant multilocular cystadenoma. These tumors are very rare, and, as mentioned by Paner and colleagues, the clinicopathologic spectrum of cystic epithelial tumors of the prostate remains to be defined. We intend to report an exceptional and, to our knowledge, first case of a prostatic giant cystic tumor consisting of a cystadenocarcinoma associated with a cystadenoma. A 50-year-old man presented with acute abdominal pain leading to the discovery of a large multicystic mass in the pelvis. Multiple surgical biopsies were performed. Pathologic examination of the biopsies showed round to ovoid dilated glandular structures with a flattened cell layer or with a papillary pseudohyperplastic to a tall columnar and stratified epithelial cell layer with some mitosis figures and prominent nucleoli. A prostatic primary tumor was diagnosed because of a positive prostatic-specific antigen (PSA) immunohistochemistry, and a mesothelial multicystic proliferation was ruled out. The glands were p63 negative and p504s positive. Those features were of a small ductal prostatic adenocarcinoma component in a prostatic and extraprostatic cystic tumor. The PSA serum level was 4 ng/ mL at the time of this first sampling. Because of the recurrence of pain and dysuria 16 months after the first surgical biopsies, a new pelvic computed tomography was performed and revealed a voluminous mass measuring 13 9 14 cm involving the perirectal and presacral area, reaching the sacral nerve roots, surrounding the rectum and the sigmoid and pushing the bladder-prostate complex to the anterior and the right. The PSA level was elevated at 14.72 ng/mL. New samples of the tumor and of the surrounding prostate were obtained by transurethral bladder resection and by transrectal biopsies. The histologic examination of the biopsies did not reveal any intraprostatic tumor but argued for a tumor developed in the periprostatic tissue. The pattern of this tumor was multicystic, and the cysts were lined by a flattened monostratified epithelium without mitosis or prominent nucleoli. These glands were p63 positive and p504s negative. These data were in favor of a benign cystic prostatic tumor consisting in a cystadenoma. However, the transurethral bladder resection samples presented some foci of prostatic ductal adenocarcinoma as described previously. Finally, the patient underwent a total pelvic exenteration 17 months after initial surgical biopsies (ie, anterior and posterior pelvectomy with colo-anal anastomosis and Bricker urinary diversion). The piece measured 16 10.5 24cm and included the urinary bladder, the prostate, the seminal vesicles, and a 24-cm-long colorectal segment (Fig. 1). An anterior-posterior section revealed a 9.5 9cm honeycomb tumor with cysts ranging from 0.2 to 1.7 cm developed from the posterior wall of the urinary bladder and posterior part of the prostatic base. This tumor extended through the perirectal adipose tissue with important hemorrhagic and necrotic changes. Seminal vesicles appeared well preserved but elongated. Several enlarged lymph nodes were identified adjacent to the urinary bladder and the rectum. Histologically, the samples from the junction between the urinary bladder and the prostate and from the posterior wall of the bladder presented the previously described features of a prostatic cystadenoma with a p63-positive and p504s-negative immunohistochemistry (Figs. 2A, C, E, G). In the retrovesical part of the tumor, the epithelium lining the glands showed various levels of atypia from a single layer of cuboid nonatypical prostatic cells with neither mitotic activity nor evident nucleoli, with columnar cells drawing papillae and glandular tubules that were p63 negative and p504s positive. These features were consistent with a cystadenocarcinoma with focal ductal features (Figs. 2A, B, D, F). No perinervous infiltration or lymphovascular invasion was noted. The tumor infiltrated the perirectal adipose tissue reaching the muscularis propria without destructing it. Seminal vesicles were