A 48-year-old man with a medical history of hypertension and no family history of prostate cancer presented with abdominal distension, lower abdominal pain, and lower urinary symptoms. Physical examination revealed a palpable mass in the lower abdomen, and a digital rectal examination detected a firm mass on the anterior side of the rectum. Laboratory tests showed an elevated PSA level (7.9 ng/mL). Imaging studies indicated a solid mass connected to the prostate\'s posterior and rectum\'s anterior walls, along with bladder compression. Transperitoneal biopsy and histological analysis led to a diagnosis of a stromal tumor with uncertain potential malignancy. Considering the absence of apparent malignancy signs and the smooth outer wall of the tumor, the patient underwent, for the first time in the literature, a robot-assisted radical extraperitoneal prostatectomy for complete macroscopic resection. The surgery involved excision of the bulky pelvic mass, preservation of the urethra, and anatomical reconstruction. The postoperative course was uneventful, and we discharged the patient with no complications. The pathological examination documented the diagnosis of multilocular prostatic cystadenoma. Post-surgery follow-up examinations, including PSA levels and imaging scans, showed no signs of tumor recurrence. At the 3-, 6-, and 9-month follow-ups, the patient was asymptomatic and had fully recovered, with no urinary or sexual dysfunction reported.

Giant multilocular prostatic cystadenoma (GMC) is an extremely rare, benign tumor seen in both adult and pediatric males. The neoplasm originates from prostatic tissue and is typically found within the rectovesical pouch, varying in both size and morphology. Microscopically, GMC contains both glandular and cystic prostatic tissue lined by cuboidal and columnar epithelium. Symptoms often arise once the pelvic mass begins to obstruct the surrounding structures and organs, although invasion into surrounding tissue is unlikely. Common symptoms include abdominal pain, urinary retention, and dysuria. The standard treatment for GMC is surgical removal of the mass with good outcomes and only 1 known case of recurrence. Here we present the case of a 14-year-old male with GMC-the youngest patient reported to date-who presented with abdominal pain, difficulty voiding, and hydroureteronephrosis.

Giant multilocular prostatic cystadenoma is a rare benign tumor that originates from the prostate gland. It usually is between the rectum and the bladder, and is composed of predominantly cystic enlarged prostatic glands in a fibrous stroma and spreads extensively in the pelvis. The mass usually causes a series of obstructive symptoms by compressing adjacent organs. Here we report a case of a giant multilocular prostatic cystadenoma in a 16-year-old patient, who is the youngest case reported up to now, complaining of difficulty in defecation.

BACKGROUND: The giant multilocular prostatic cystadenoma is a very rare benign tumor of the prostate gland. It is composed of predominantly cystic enlarged prostatic glands in a fibrous stroma and spreads extensively into the pelvis. Because of the large size at the time of diagnosis, it is not always possible to determine the exact point of origin for these multilocular cystic neoplasms. Thus, diagnosis before histological examination of a surgical specimen is often difficult. Here, we present a case involving one of the largest giant multilocular prostatic cystadenomas reported in the literature and discuss preoperative diagnoses and appropriate surgical approaches for this rare retroperitoneal tumor.
METHODS: A 50-year-old man presented with a 2-year history of abdominal distension and lower urinary symptoms. Enhanced CT showed a large retroperitoneal mass with multiple septations in the pelvis and lower abdomen, measuring 30 cm in size, surrounding the rectum and displacing the bladder, prostate, and seminal vesicle to the right anterior side. MRI showed multiple cysts with a simple fluid appearance on T2-weighted images and enhanced solid components on gadolinium-enhanced fat-saturated T1-weighted images, suggesting the retroperitoneal mass as leiomyoma with cystic degeneration or perivascular epithelioid cell tumor. Biopsy of the mass showed a spindle cell tumor with focal smooth muscle differentiation. Differential diagnosis comprising leiomyoma, low-grade leiomyosarcoma, and perivascular epithelioid cell tumor was made. Complete resection of the tumor with low anterior resection of the rectum was performed. The tumor was solid with multilocular cavities containing blackish-brown fluid and measured 33 × 23 × 10 cm. Histologically, the tumor was composed of variously sized dilated glandular structures lined by prostatic epithelia surrounded by fibromuscular stroma. The prostatic nature of the lesions was confirmed by immunohistochemical staining of the epithelium for prostate-specific antigen. Thus, pathological diagnosis was a giant multilocular prostatic cystadenoma.
CONCLUSIONS: We present our experiences with one of the largest giant multilocular prostatic cystadenomas. When a retroperitoneal huge lesion with locular cavities fills the pelvis in a male patient, the possibility of giant multilocular prostatic cystadenoma should be considered before planning for retroperitoneal tumor treatment.