Detection of relatively poor but definitive blood supply in prostate stromal sarcoma using transrectal ultrasonography with superb microvascular imaging.

A 23-year-old man presented with complaints of macrohematuria and hematospermia and was referred to our hospital for further examination. Magnetic resonance imaging revealed a round 30 × 25 mm tumor in the right peripheral zone; hence, a rare prostate tumor was suspected. Grayscale transrectal ultrasonography (TRUS) was performed using the Aplio-i800 PVL-715RST-transducer and revealed a well-defined round tumor. Although regular color Doppler flow imaging could not detect internal blood flow, superb microvascular imaging (SMI) identified the low-velocity blood flow in the tumor. Based on the results of a TRUS-guided targeted biopsy assisted by SMI, the patient was diagnosed with stromal sarcoma. He underwent total pelvic exenteration with construction of ileal conduit and colostomy, the tumor was finally diagnosed as prostate stromal sarcoma (PSS). Since PSS is a rare malignant prostate tumor, reports on the characteristic findings in imaging tests are scarce. To the best of our knowledge, this study reports the first case in which a poor internal blood flow was detected in PSS, but not through regular color Doppler flow imaging. SMI revealed that the blood flow signal to the PSS was relatively poor; however, its definite presence was confirmed, suggesting a malignant disease with relatively poor blood supply and the findings of SMI would assist the adequate targeted biopsy-sampling from the presence site of viable cells with the blood supply.