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Suspected clinically localised prostate cancer after previous negative biopsy — MSRA MCQ

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HardPI-RADSSuspected clinically localised prostate cancer after previous negative biopsyMSRA

A 66-year-old man is re-referred with a rising PSA after a benign systematic transrectal biopsy 18 months ago. He remains fit for radical treatment if clinically significant prostate cancer is diagnosed. His PSA is 6.3 micrograms/L, MRI-derived prostate volume is 60 mL (PSA density 0.105 ng/mL/mL), and digital rectal examination is benign. Multiparametric MRI demonstrates two lesions. In the right posterolateral peripheral zone, there is an 8 mm focal lesion with mildly hypointense ADC signal and mildly hyperintense high-b-value DWI signal (DWI score 3). It shows focal early enhancement corresponding to the diffusion abnormality. In the left transition zone, there is a 12 mm circumscribed nodule with an incomplete capsule, consistent with an atypical benign prostatic hyperplasia nodule (T2-weighted score 2); it is markedly hypointense on ADC and markedly hyperintense on high-b-value DWI (DWI score 4), with focal early enhancement. There is no extracapsular extension. The local radiologist assigns an overall MRI Likert score of 4. Which is the most appropriate interpretation and immediate diagnostic management?

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Correct answer: E — Classify the peripheral-zone lesion as the PI-RADS 4 index lesion and the atypical transition-zone nodule as PI-RADS 3; discuss significant disease at MDT with a view to repeat MRI-influenced biopsy.

The peripheral-zone lesion is PI-RADS 4: in the peripheral zone, DWI is dominant, but a DWI score 3 lesion is upgraded to category 4 when there is corresponding focal early enhancement on DCE MRI. Its 8 mm size and absence of extracapsular extension mean there is no basis for PI-RADS 5. The transition-zone lesion is an atypical BPH nodule with T2 score 2. Under PI-RADS v2.1, marked diffusion restriction (DWI 4 or 5) upgrades such a lesion from category 2 to category 3. DCE does not further upgrade a transition-zone lesion, where T2-weighted imaging is the dominant sequence. The higher-category peripheral-zone lesion is therefore the index lesion. Most importantly in this UK pathway, he has had a previous negative biopsy and now has MRI Likert 4. NICE advises MDT discussion of the possibility of significant disease, with a view to repeating biopsy. His PSA density below 0.15 ng/mL/mL does not justify surveillance when MRI suspicion is Likert 3 or above; that threshold is used principally to guide management after low-risk MRI (Likert 1–2).

Reference: NICE NG131: Prostate cancer: diagnosis and management, recommendations (2019; checked 16 August 2026) — https://www.nice.org.uk/guidance/ng131/chapter/Recommendations Prostate Imaging Reporting and Data System Version 2.1: 2019 Update of Prostate Imaging Reporting and Data System Version 2 (2019) — https://pubmed.ncbi.nlm.nih.gov/30898406/ PI-RADS v2.1: What has changed and how to report (2021) — https://pubmed.ncbi.nlm.nih.gov/34230862/