The ultrasound appearances of prostatic cancer with histological correlation.

An analysis of the ultrasound appearances of the prostate with its capsule and periprostatic structures was performed in 221 patients with a histologically confirmed diagnosis of prostatic cancer. The cancers were histologically graded into well, moderate and poorly differentiated adenocarcinoma and transitional cell carcinoma. The results of this study indicate that an ill-defined hypoechoic area is the commonest appearance of prostatic cancer; this was seen in 96% of our 221 patients. The cancers were staged by ultrasound into confined (T0, T1, T2) and unconfined (T3) cancers. A breach of the capsule was seen in 55% of cases. In this unconfined group all cancers were hypoechoic in comparison with 92% in the confined group. In the confined cancer group the areas of abnormal echogenicity were present in more than one prostatic quadrant in 76%. Mostly commonly two prostatic quadrants were affected. The abnormal echogenicity was noted in the posterior quadrants of the prostate more commonly (58%) than in the anterior quadrants. The prostate gland appeared round in 67%, semicircular in 25% and crescentic in 8%. The gland was symmetrical in 68%. The prostatic capsule appeared regular in 86% of patients with a confined cancer. In 70% of cases of extensive but confined cancer there was loss of demarcation between the central and peripheral zones of the gland. The unconfined cancer group all had a breach of the capsule and all glands were heterogeneous due to hypoechoic areas. The breach affected more than one quadrant in 81% and most commonly the capsular breach involved two prostatic quadrants. An anterior breach of the capsule was noted much more frequently than a posterior breach. Forty-four per cent of cases had three or four quadrants of the gland involved. In 3% of cases of proven prostatic cancer no definite ultrasound abnormality could be detected. Calcification was seen within the gland in association with the cancer in 63% with approximately equal frequency in confined and unconfined disease. The seminal vesicles showed definite evidence of infiltration in 10%. Both seminal vesicles were seen in 61% and thought to be normal. In 8% only one was seen. Failure to demonstrate either seminal vesicle occurred in 21%. There was no correlation between the ultrasound appearances of prostatic cancer and the histological grading of the tumour.