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Suspected clinically localised prostate cancer with low-suspicion MRI but elevated PSA density — MSRA MCQ

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HardPI-RADSSuspected clinically localised prostate cancer with low-suspicion MRI but elevated PSA densityMSRA

A 67-year-old man is investigated on the suspected prostate cancer pathway. He would be suitable for radical treatment if clinically significant prostate cancer were diagnosed. His PSA is 8.1 micrograms/L and MRI-derived prostate volume is 45 mL (PSA density 0.18 ng/mL/mL). Digital rectal examination is benign. He has not previously had a prostate biopsy. Multiparametric MRI shows a 12 mm homogeneous, circumscribed transition-zone nodule with an incomplete capsule, giving a T2-weighted score of 2 (an atypical benign prostatic hyperplasia nodule). There is no focal marked diffusion restriction on ADC or high-b-value diffusion-weighted imaging (DWI score 2), no focal early enhancement and no extracapsular extension. The lesion is assigned PI-RADS v2.1 category 2, and the overall MRI Likert score is 2. Which reporting interpretation and immediate diagnostic management is most appropriate?

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Correct answer: B — Classify the lesion as PI-RADS 2 and offer systematic prostate biopsy

This is a PI-RADS v2.1 category 2 transition-zone lesion. An incompletely encapsulated but homogeneous circumscribed transition-zone nodule is an atypical BPH nodule (T2 score 2). It is upgraded only when there is marked diffusion restriction (DWI score 4 or 5); this lesion has DWI score 2, so neither its incomplete capsule nor its size makes it PI-RADS 3 or 4. However, MRI categorisation does not end the diagnostic decision in UK practice. Although biopsy may be omitted after a Likert 1–2 MRI when overall suspicion is low, NICE advises biopsy where suspicion remains strong, including PSA density above 0.15 ng/mL/mL. His PSA density is 0.18 ng/mL/mL and he is fit for radical treatment. With no MRI target, the appropriate biopsy is systematic. A wrongly upgrades the lesion despite absent marked diffusion restriction. B and C would be appropriate only if low-risk MRI findings were accompanied by low overall clinical suspicion, such as PSA density at or below 0.15 ng/mL/mL. E incorrectly treats an atypical BPH nodule as a high-suspicion transition-zone mass and assumes a target exists for MRI-influenced biopsy.

Reference: NICE NG131: Prostate cancer: diagnosis and management — MRI and biopsy recommendations (2019; page checked 2026) — https://www.nice.org.uk/guidance/ng131/chapter/Recommendations Prospective PI-RADS v2.1 Atypical Benign Prostatic Hyperplasia Nodules With Marked Restricted Diffusion (2020) — https://pubmed.ncbi.nlm.nih.gov/32876473/