Presentation
Elevated prostate-specific antigen (PSA): 5.8 ng/mL.
Patient Data
Findings:
Quality: some geometric distortion on DWI, does not compromise diagnostic confidence
Prostate size: 42 x 40 x 40 mm (CC x AP x ML) ≈33 mL, PSA density ~0.17 ng/mL2
Hemorrhage: none
Peripheral zone (PZ): bilateral linear/wedge-shaped hypointensities, focal finding in the left posterior mid gland and basal zones as below:
Transition zone (TZ): moderate heterogeneity, some BPH nodules in the apical zone, focal finding in the left posterior mid gland and basal zones as below:
Focal lesion #1 (PZpm/pl and TZp):
- location: left mid gland and basal posterior peripheral zone (PZpm/pl) and left transition zone (TZp)
- lesion size: ~20 x 16 mm
- T2w: heterogeneous, low signal in the posteromedial peripheral zone (PZpm) and homogeneous, moderately hypointense signal in the posterior transition zone (TZp) with indistinct/obscured prostate pseudocapsule – “erased charcoal sign” – category 5/5
- DWI: focal slightly to markedly hyperintense on DWI (b1000) and markedly hypointense on ADC in the posterior transition zone (TZp) and in the posteromedial part of the peripheral zone (PZpm) - category 3/5 and 5/5, respectively
- DCE: focal early enhancement - positive
Prostate margin: capsular contact, no bulge or breach
Overall PI-RADS category: 5
Neurovascular bundles: probably not involved
Seminal vesicles: contracted, not involved
Lymph nodes: multiple small oval iliac lymph nodes (up to 6 mm size, fatty hilum, smooth margins)
Pelvic bones: no osseous metastases
Other pelvic organs: normal
Impression:
A very highly suspicious lesion in the left peripheral zone (PZpm/pl) and left posterior transition zone (TZp) - PI-RADS 5.
A prostate biopsy was recommended.
After patient preparation and positioning as well as acquisition of planning sequences, the suspicious lesion in the left mid gland and basal, posterior peripheral and the transition zone is re-identified on the images, marked and locked with the navigation software.
Two biopsy cores are obtained from the lesion with a 150 cm 18G biopsy needle, registered and sent to pathology.
Case Discussion
This case demonstrates a PI-RADS 5 lesion of the posterior transition zone and the posteromedial and posterolateral peripheral zone. The case also depicts the “erased charcoal sign”, which refers to an appearance of a homogeneously T2 low-signal lesion in the transition zone of the prostate with indistinct margins. In this case, it is the smudged appearing border between transition and peripheral zones, which is also referred to as “pseudocapsule” or “surgical capsule”.
Histology of the MR-in bore biopsy revealed an infiltrate of an adenocarcinoma (modified Gleason score 4+5=9, high grade) within both cores.
The patient underwent radical retropubic prostatovesiculectomy with pelvic lymphadenectomy.
Final histology of the prostatovesiculectomy preparation revealed poorly differentiated acinar adenocarcinoma in both lobes (~10% right lobe, ~30% left lobe) with perineural tumor growth.
Gleason score 4+5=9, ISUP grade 5.
Resection margins and seminal vesicles were free from tumor cells.
Tumorclassification: pT2c, pN0, R0.
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