Sarcoma of the Prostate

Transcription

1 Case Report Sarcoma of the Prostate Sonographic Findings and Pathologic Correlation Ronald Stilgenbauer, RT(R), RDMS, Matthew Benedict, MD, Robert Bamshad, MD, Alexander Viduetsky, PhD, RDMS, RDCS, RVT Sarcoma of the prostate is a rare malignancy that affects younger men and has a poorer prognosis in comparison with prostate cancer. Transrectal ultrasound (TRUS) and ultrasound-guided biopsy of the prostate are the main methods for early diagnosis. Treatment of prostate sarcoma consists of radical surgery, chemotherapy, and radiotherapy. Absence of metastasis at the time of diagnosis and negative surgical margins are more important for prognosis than tumor size, grade, and histologic subtype. Case Report Abbreviations TRUS, transrectal ultrasound Received June 27, 2007, from the Beverly Tower Wilshire Advanced Imaging Center, Beverly Hills, California USA (R.S., M.B., A.V.); and Cedars-Sinai Medical Center, Los Angeles, California USA (R.B.). Revision requested July 24, Revised manuscript accepted for publication August 2, Address correspondence to Alexander Viduetsky, PhD, RDMS, RDCS, RVT, Beverly Tower Wilshire Advanced Imaging Center, 8750 Wilshire Blvd, Suite 100, Beverly Hills, CA USA. a_viduetsky@msn.com A 27-year-old man was referred to our diagnostic center for TRUS and prostate biopsy because of pollakiuria, dysuria, painful defecation, abnormal findings at physical examination, and abnormal computed tomographic findings. Digital rectal examination at the urologist s office revealed a substantially enlarged nodular prostate. The complete blood cell count was normal. Urinalysis revealed minor hematuria. Computed tomography (performed at another facility) showed a substantially enlarged prostate, measuring at least 8 6 cm, with several areas of low density within the prostatic gland. The enlarged prostate slightly compressed the anterior wall of the rectum. A TRUS examination of the prostate was carried out according to our routine protocol with a LOGIQ 9 scanner (GE Healthcare, Milwaukee, WI). Multiple transverse coronal and longitudinal sagittal images were acquired 2007 by the American Institute of Ultrasound in Medicine J Ultrasound Med 2007; 26: /07/$3.50

2 Sarcoma of the Prostate immediately before biopsy with an 8.0-MHz endoluminal transducer. The patient was in the left lateral decubitus position, with the knees slightly bent, during both the regular TRUS examination and the TRUS-guided biopsy procedure. The prostate gland was markedly enlarged, measuring 7.1 cm in transverse, 7.3 cm in longitudinal, and 5.5 cm in anteroposterior dimensions. The prostate volume measured 150 ml. The entire prostate gland was markedly nodular and heterogeneous (Figure 1). The posterior and lateral walls of the prostate had focal protrusions and were poorly delineated, indicating possible extracapsular extension of the present pathologic process. The urethra, ejaculatory ducts, and seminal vesicles were difficult to assess because of the mass effect of the prostate. A cm müllerian duct cyst was incidentally noted at the left side from the midline, secondary to the mass effect from the prostate gland (Figure 2). Under TRUS guidance, an 18-gauge 20-cm core biopsy needle (Magnum; Bard Peripheral Technologies, Covington, GA) was used to obtain 12 samples from the prostate gland. Six samples were obtained from the left side of the prostate: 2 from the base, 2 from the mid gland, and 2 from the apex. Six more samples were obtained from the right side in the same manner (Figure 3). The patient tolerated the procedure adequately with no immediate postprocedure complications. The patient was discharged home in stable condition. Figure 1. A, Transverse view, base. An enlarged nodular prostate with irregular anterior and lateral margins and multiple internal hypoechoic regions are shown. B, Transverse view, mid portion. Bulging anterior and lateral walls are clearly shown; heterogeneous parenchyma with multiple hypoechoic areas is also visible on this image. C, Transverse view, apex. The contours are not as bulging as in the base and mid sections, but heterogeneous morphologic characteristics of the gland are present. D, Longitudinal view, mid. The posterior wall of the prostate has an irregular and poorly delineated contour, which could indicate extracapsular extension of the pathologic process. The prostatic urethra is not clearly shown because of the mass effect of the prostate. A B C D 1790 J Ultrasound Med 2007; 26:

3 Stilgenbauer et al Figure 2. Müllerian duct cyst at the left side from the midline. This shift from the midline is a consequence of the mass effect of the substantially enlarged prostate. The core biopsy specimens were analyzed at the pathology laboratory. The biopsies showed diffuse involvement of prostate tissue by a malignant neoplasm characterized by solid sheets of elongated spindle-shaped cells (Figures 4 and 5). The nuclei of these cells were oval and elongated, with delicate vacuolated chromatin and a high rate of mitotic activity: up to 8 mitoses per single high-power field (Figure 6). Cytologic atypia was moderate. Immunohistochemical studies showed no reactivity of neoplastic cells with antibodies against S-100 protein, desmin, smooth muscle actin, keratin AE1/AE3, cytokeratin 19, cytokeratin 7, epithelial membrane antigen, CD34, myoglobin, MyoD1, CD99, estrogen receptor, progesterone receptor, androgen receptor, and CD117. Neoplastic cells showed cytoplasmic reactivity with antibodies against BCL-2. Special features of differentiation, either histologic or immunophenotypic, of this spindle cell sarcoma were not noted. Hence, this neoplasm was classified as intermediate- to high-grade (grade 2 3) undifferentiated sarcoma, with diagnostic considerations including synovial sarcoma and prostatic stromal sarcoma. The patient was taking chemotherapy, after which he was scheduled to undergo radical prostatectomy. Discussion Prostate cancer is the most frequent male malignancy, excluding skin cancer, in the United States, representing 33% of all estimated male cancer cases in Prostate cancer is the third leading cause of death by cancer, after lung/bronchus and colon/rectum cancers, representing 9% of all estimated cancer deaths in men in Rarely registered prostate tumors include leiomyoma, lymphoma, squamous cell carcinoma, and sarcoma. They account for less than 5% of malignant tumors. 2 Histologically, the main subtypes of prostate sarcoma consist of leiomyosarcoma, rhabdomyosarcoma, fibrosarcoma, spindle cell sarcoma, synovial sarcoma, prostatic stromal sarcoma, and undifferentiated sarcoma. Figure 3. Core biopsy of the prostate under TRUS guidance. A biopsy needle is shown at the bottom as a hyperechoic line following the dotted line guide. Figure 4. Core biopsy specimen showing a spindle cell neoplasm at low magnification (intermediate- to high-grade [grade 2 3] undifferentiated sarcoma). J Ultrasound Med 2007; 26:

4 Sarcoma of the Prostate Figure 5. Core biopsy specimen showing a spindle cell neoplasm at high magnification. Prostate sarcoma occurs more often in younger men, before 40 years, in comparison with prostate cancer, which affects mostly older men. 3,4 The most common clinical manifestations of prostate sarcoma are dysuria and pollakiuria. Prostates affected by sarcoma are diffusely enlarged and firm or rubbery, frequently with soft necrotic areas; these are different from the typical appearances of prostatic carcinoma. 4 The regularity of the prostatic contour is an important characteristic in the assessment of a malignant process. The lateral aspects of the posterior prostate and the entrances of the superior and inferior inner vascular bundles are particularly important in the evaluation of the contour s irregularities. Careful scanning of the fat plane adjacent to the posterior prostate capsule could detect extracapsular extensions of a malignant tumor and possible rectal wall involvement. 4 In Figure 6. Core biopsy specimen showing mitotic activity. our case, focal irregularities of the posterior prostatic wall (evidence of extracapsular growth) could be seen on the midline sagittal images. The prostate volume in our patient (150.0 ml), exceeded recently published upper ranges for adenocarcinoma of the prostate (108.2 ml), prostate intraepithelial neoplasia (102.0 ml), and benign prostatic hypertrophy (144.7 ml). 5 It has been reported that 75% to 80% of prostate cancers develop in the peripheral zone, 10% to 20% in the transitional zone, and 5% to 10% in the central zone. Cancerous tumors are usually detected within 0.3 cm of the capsule. 6 Diffuse prostatic cancers could mimic diffuse benign prostate diseases such as nodular hyperplasia, nonspecific chronic inflammation, malakoplakia, and tuberculosis. However, a markedly enlarged prostate with a bulging contour, poorly demarcated hypoechoic areas, and scattered calcifications suggests diffuse cancer rather than benign disease. 7 The B-mode images of the prostate in our case, correlated with the gray scale characteristics of diffuse cancer, except scattered calcifications, which we did not observe. Conducting a literature review, we found that color and power Doppler imaging are valuable tools for the assessment of prostatic lesions, 5,7 and we intend to introduce these methods in our current TRUS protocols. (We did not use Doppler interrogation in this case.) Poorly defined margins of the prostate (especially the posterior wall) and marked heterogeneity, with embedded hypoechoic regions, are suspicious for either diffuse cancer or sarcoma of the prostate. The young age of a patient (<40 years), very large prostatic volume (>145 ml), and absence of scattered calcifications suggested sarcoma rather than diffuse cancer of the prostate. Prostate biopsy under TRUS guidance, with a subsequent pathologic analysis, remains the definitive procedure for the correct diagnosis. Early surgery, chemotherapy, and radiotherapy are the best methods of treatment. The longterm survival rate for adults with prostate sarcoma is poor. Factors predictive of long-term survival are negative surgical margins and absence of metastatic disease at presentation. Tumor size and grade and the histologic subtype of prostate sarcoma have no notable influence on actuarial survival J Ultrasound Med 2007; 26:

5 Stilgenbauer et al References 1. American Cancer Society. Cancer Statistics 2006 Presentation. Atlanta, GA: American Cancer Society Inc; Available at content/pro_1_1_cancer_statistics_2006_presentation.asp. 2. Gourtsoyiannis NC, Ros PR (ed). Radiologic-Pathologic Correlations From Head to Toe: Understanding the Manifestations of Disease. Berlin, Germany: Springer-Verlag; Chen HJ, Xu M, Zhang L, Zhang YK, Wang GM. Prostate sarcoma: a report of 14 cases. Zhonghua Nan Ke Xue 2005; 11: Hricak H, Carroll PR (ed). The Radiologic Clinics of North America. The Prostate Gland: A Clinically Relevant Approach to Imaging. Philadelphia, PA: WB Saunders Co; Arger PH, Malkowicz SB, VanArsdalen KN, Sehgal CM, Holzer A, Schultz SM. Color and power Doppler sonography in the diagnosis of prostate cancer: comparison between vascular density and total vascularity. J Ultrasound Med 2004; 23: Dogra V, Rubens DJ. Ultrasound Secrets. Philadelphia, PA: Hanley & Belfus; Cho JY, Kim SH, Lee SE. Diffuse prostatic lesions: role of color Doppler and power Doppler ultrasonography. J Ultrasound Med 1998; 17: Sexton WJ, Lance RE, Reyes AO, Pisters PW, Tu SM, Pisters LL. Adult prostate sarcoma: the M. D. Anderson cancer center experience. J Urol 2001; 166: J Ultrasound Med 2007; 26: