Solitary pelvic nodule: diagnosis of metastatic prostate cancer by endoscopic ultrasound-guided, fine-needle aspiration

Solitary pelvic nodule: diagnosis of metastatic prostate cancer by endoscopic ultrasound-guided, fine-needle aspiration

THE AMERICAN JOURNAL OF GASTROENTEROLOGY © 2000 by Am. Coll. of Gastroenterology Published by Elsevier Science Inc. Vol. 95, No. 9, 2000 ISSN 0002-92...

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THE AMERICAN JOURNAL OF GASTROENTEROLOGY © 2000 by Am. Coll. of Gastroenterology Published by Elsevier Science Inc.

Vol. 95, No. 9, 2000 ISSN 0002-9270/00/$20.00 PII S0002-9270(00)01127-8

Solitary Pelvic Nodule: Diagnosis of Metastatic Prostate Cancer by Endoscopic Ultrasound-Guided, Fine-Needle Aspiration Timothy A. Woodward, M.D., David M. Menke, M.D., and Steven J. Buskirk, M.D. Division of Gastroenterology, Mayo Clinic Jacksonville, Jacksonville, Florida

ABSTRACT Prostate cancer manifesting as an isolated perirectal mass is a rare occurrence. The following is a report of a single pelvic nodule that was determined to be metastatic prostate cancer by endoscopic ultrasound-guided, fine-needle aspiration. (Am J Gastroenterol 2000;95:2372–2373. © 2000 by Am. Coll. of Gastroenterology)

CASE REPORT The patient is a 70-yr-old man who had radical prostatectomy and external-beam radiation treatment 10 yr ago for prostate cancer. Radiographic studies and prostate-specific antigen (PSA) were within normal limits for approximately 2 yr; however, a rising PSA led to a bilateral orchiectomy. PSA remained stable until 3 yr ago, at which point it had risen from 0.2 ng/ml to the most recent PSA of 2.2 ng/ml. In addition, the patient developed a burning discomfort in the rectum. His physical examination was unremarkable. A CT scan of the abdomen and pelvis was remarkable only for a 1.4-cm, soft tissue density in the left perirectal fat that was not present on the pelvic CT 3 yr previously. A radionuclear bone scan was negative for skeletal metastasis. Flexible sigmoidoscopic examination was unremarkable. Endoscopic ultrasound (EUS) was subsequently done for better assessment and possible fine-needle aspiration (FNA) of the perirectal nodule. A radial scanning endosonoscope (GFUM-20; Olympus) was used with a water-filled balloon and instillation of water into the rectum. Ultrasound scanning at 7.5 MHz was performed. Endosonographic evaluation revealed, 15 cm from the anal verge, a well circumscribed, hypoechoic 1.43-cm ⫻ 1.23-cm nodule approximately 1 cm away from the rectal wall (Fig. 1). After removal of the radial endosonoscope, the linear array endosonoscope (FG-32UA; Pentax) was introduced and advanced to the aforementioned area. Under endosonographic visualization, a single pass was made with the Handke-Vilmann fine-needle aspiration system. Review by an on-site cytopathologist confirmed the lesion to be prostate adenocarcinoma.

Figure 1. Endosonographically imaged pelvic nodule undergoing fine-needle aspiration.

DISCUSSION Transrectal ultrasound via the rigid ultrasound probe has been used for radiological assessment of the prostate throughout the past decade (1). Additionally, rectal endosonography has been useful in the staging of rectal cancers (2). There have been reports of prostate cancer mimicking a primary rectal tumor diagnosed by EUS (3, 4), and incidental discovery of a prostate cancer after transrectal sonography for rectal cancer staging (5). Sonographically, prostate carcinomas are usually hypoechoic (6). Hypoechoic lesions ⱖ1 cm have a positive predictive value for cancer ranging between 13% and 41% (7). Atypical metastases of prostate cancer have been reported (8). EUS-FNA has been used transrectally in the diagnosis of gynecological lesions (B. Hoffman, R. Hawes, personal communication). Regarding the use of antibiotics in the setting of rectal EUS-FNA, we currently reserve the use of antibiotics primarily for cystic lesions, as reported by other EUS centers (B. Hoffman, R. Hawes, personal communication). As of this date, this is the first published report of the cytopathological diagnosis of metastatic prostate carcinoma by EUS-FNA of a perirectal nodule.

AJG – September, 2000

Reprint requests and correspondence: Timothy A. Woodward, M.D., Mayo Clinic Jacksonville, Division of Gastroenterology, 4500 San Pueblo Road, Jacksonville, FL 32224. Received Oct. 6, 1998; accepted Feb. 23, 1999.

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