Transrectal Ultrasound Appearance of Transitional Cell Carcinoma Involving the Prostate

Pictorial review: Unusual tumours involving the prostate: radiological-pathological findings

The appearance of several unusual tumours in the prostate has resulted in questions being raised concerning their histogenesis; moreover, some of these tumours have prognoses that are quite unlike those of prostatic adenocarcinoma. Unusual neoplasms involving the prostate have been described in recent years, including mucinous cystadenocarcinoma, neuroendocrine cancer, lymphoma, spindle cell neoplasm, squamous cell carcinoma and transitional cell carcinoma. Radiological findings can overlap, and play limited roles in the diagnoses of these entities. However, knowledge of the radiological findings in these conditions can be helpful in making differential diagnoses. Images of prostate lesions using several imaging modalities, including transrectal ultrasound, MRI and CT, as well as available pathological images of such lesions, are presented in this article.

The prostatic gland: malignancies other than adenocarcinomas

Many rare variants of prostatic carcinoma have been described and characterized in recent years. Accurate diagnosis of these variants is necessary in order to determine appropriate therapy. Unusual tumors arising in the prostate raise questions of histogenesis, and may carry a better or worse prognosis than typical adenocarcinoma. Virtually the entire spectrum of cellular differentiation has been observed within prostatic epithelium, and rare neoplasms exhibit these unusual forms of differentiation as the chief component of the tumor. Except in sarcoma (marked prostatic enlargement), imaging plays a limited role in the diagnoses of these entities. Biopsy and histologic diagnoses are essential and the role of imaging is restricted to the evaluation of locoregional and distant spread of the disease.

Transrectal ultrasound appearance of radiation-induced prostatic sarcoma

BACKGROUND

Delayed development of prostatic sarcoma is a rare complication of prostatic pelvic irradiation. The transrectal ultrasound appearance of this lesion has not been previously described.

METHODS

Three cases of radiation-induced prostatic sarcoma are presented, with emphasis on the transrectal ultrasound findings.

RESULTS

An irregular, hypoechoic prostatic mass with an anechoic area consistent with the echogenicity of muscle and/or necrosis was found in all 3 patients. This appearance is distinctly dissimilar from prostatic adenocarcinoma.

CONCLUSIONS

The sonographic finding of an irregular, hypoechoic prostatic mass with an anechoic area should raise suspicion for prostatic sarcoma in patients with a history of pelvic irradiation who develop an abnormal prostate on rectal examination and/or worsening voiding symptoms despite a normal serum prostate-specific antigen level.

Transrectal ultrasound appearance of prostatic granulomas secondary to bacillus Calmette-Guerin instillation

PURPOSE

To our knowledge the transrectal ultrasound appearance of prostatic granulomas occurring after intravesical bacillus Calmette-Guerin (BCG) therapy has not been thoroughly described.

MATERIALS AND METHODS

A total of 13 men with a history of transitional cell carcinoma of the bladder treated with intravesical BCG underwent transrectal ultrasound followed by prostate biopsy and/or cystoprostatectomy.

RESULTS

Of the 13 patients studied 9 (69.2%) had intensely hypoechoic lesions anteriorly in the transition zone of the prostate on ultrasound images. The lesions were histologically proved to be necrotizing granulomas.

CONCLUSIONS

Prostatic granulomas secondary to BCG instillation appear as distinct, intensely hypoechoic anterior lesions within the transition zone of the prostate. Prostatic adenocarcinoma arising in the transition zone is usually not visible and would not be easily confused with granulomas. However, since transitional cell carcinoma involving the prostate can appear hypoechoic in the transition zone, transrectal or transurethral tissue sampling may be indicated.

Orthotopic bladder substitutes: histopathologic risk factors

Prostate glands from 150 patients with carcinoma of the bilharzial bladder who underwent cystoprostatectomy were studied histopathologically by step sections. Prostatic urethral involvement by urothelial carcinoma was noted in 13 out of 96 (13.5%) and 5 out of 40 (12.5%) squamous and transitional cell tumors, respectively. None of the 12 adenocarcinomas and the two undifferentiated tumors showed involvement. Prostatic urethral involvement was as high as 19% in basal tumors and 26.7% in multifocal tumors compared to only 6.5% when the tumors occupied the bladder body. There was a significant increase in the incidence of prostatic urethral involvement from 9.5 to 35% when the prostate gland was involved. Prostate gland was involved in 20 out of 150 (13.3%). The bladder tumor was basal and infiltrating the prostate in 18 such cases. Seminal vesicles were infiltrated in 6 cases from the adjacent basal bladder tumors. We conclude that patients with basal or multifocal tumors are risky regarding bladder substitution and we recommend routine diagnostic transurethral prostatic biopsies and frozen sections from the site of urethral transection during cystoprostatectomy whenever bladder substitution controlled by the urethral sphincter is considered.

Transrectal ultrasound in the evaluation of rhabdomyosarcoma involving the prostate

OBJECTIVE

To evaluate transrectal ultrasound as a means of diagnosis and of monitoring patients with rhabdomyosarcoma involving the prostate.

PATIENTS AND METHODS

Serial transrectal ultrasonography was utilized to evaluate prostatic rhabdomyosarcoma in three patients.

RESULTS

Unlike prostatic adenocarcinoma and transitional cell carcinoma involving the prostate, which are predominantly hypoechoic, the echogenicity of rhabdomyosarcoma is similar to that of the normal prostate. Transrectal ultrasound provided a simple means of monitoring prostate size and sampling tissue in these patients.

CONCLUSION

Transrectal ultrasound imaging can be useful in both diagnosis and evaluation of treatment response as well as provide easy access for biopsies in patients with rhabdomyosarcoma involving the prostate.

Efficacy of transrectal ultrasound for identification of clinically undetected prostate cancer

A total of 51 patients underwent transrectal ultrasound of the prostate before radical cystoprostatectomy for transitional cell carcinoma of the bladder. Each had a normal prostate by digital rectal examination, no history of prostatic adenocarcinoma and no invasion of the prostate by transitional cell carcinoma. Real-time and step-sectioned ultrasound images were interpreted at the time of sonography and results were compared to pathological examination of the step-sectioned prostate specimen. When adenocarcinoma was identified in the specimen, cancer volume was determined. Positive ultrasound scans consisted of those exhibiting hypoechoic lesions. Hypoechogenicity due to transurethral resection defects, benign hyperplasia, vascular structures or shadowing from calcifications was not considered positive. Of 51 patients 27 (52.9%) exhibited no abnormality on ultrasound and were free of cancer in the prostate specimen, while 8 (15.7%) demonstrated a hypoechoic lesion that was proved to be prostate cancer. Seven patients (13.7%) with normal transrectal ultrasound scans had adenocarcinoma of the prostate, while 9 (17.6%) had lesions on ultrasound but no cancer. Based on these results, transrectal ultrasound has a sensitivity of 53.3% and a specificity of 75%. Further analysis reveals that transrectal ultrasound is more accurate in the detection of cancers of greater than 0.20 cc in volume than those of 0.20 cc or less. Transrectal ultrasound also is more accurate in the detection of peripheral zone than transition zone cancers.