Presentation
Known prostate cancer on androgen deprivation therapy (ADT) for 9 weeks - radiation therapy planning. Prostate specific antigen (PSA) - 2 months ago: 37 ng/mL.
Patient Data
Findings:
Quality: no major artefacts
Prostate size: 41 x 35 x 35 mm (CC x AP x ML) ≈26 mL.
Hemorrhage: none
Peripheral zone (PZ): diffusely hypointense on T2 and ADC and hyperintense on b1400
Transition zone (TZ): diffusely hypointense, indistinct margins of the pseudocapsule, loss of zonal boundaries
Prostate margin: broad capsular contact
Neurovascular bundles: close proximity, probably involved
Seminal vesicles: diffuse hypointensity along the ejaculatory duct and inferior portions of both seminal vesicles
Lymph nodes: oval external iliac lymph nodes (up to 5 mm size, fatty hilum, smooth margins)
Pelvic bones: small lesion in the right femoral head very likely bone island, no definite signs of bony metastasis
Side note: bilateral ureteric stents with the tip in the bladder
Impression:
Shrunken prostate in a histologically proven prostate cancer with infiltration of both lobes on androgen deprivation therapy.
Signs of seminal vesicle invasion.
MRI putative stage: cT3bNxMx
Key findings:
A small, markedly hypointense prostate with loss of zonal boundaries can be seen on the T2w and ADC images. There is some signal intensity of the prostatic gland on the DWI (b1400), more pronounced than the background (red arrows) with corresponding signal loss in the ADC images (blue arrows). However, the differentiation of tumor margins is compromised.
Marked hypointensity within the inferior portions of the seminal vesicles on T2w and ADC images together with increased signal in the b1400 images are highly suggestive of seminal vesicle invasion.
Biopsy results:
Histology of the systematic biopsy performed about 2 months earlier showed an acinar adenocarcinoma (modified Gleason score 4+4=8, ISUP grade 4/5) within 12/12 cores. There was also perineural nerve sheath infiltration bilaterally. TNM: pT3a
Case Discussion
This case illustrates an already histologically proven bilateral prostate cancer on androgen deprivation therapy (ADT).
Histology of the systematic biopsy was showed an acinar adenocarcinoma (modified Gleason score 4+4=8, ISUP grade 4/5) within 12/12 cores. There was perineural nerve sheath infiltration bilaterally.
Biparametric MRI was done for radiation therapy planning and staging purposes.
The diffuse low signal intensity of the whole prostate gland in T2w and ADC images with loss of zonal boundaries and gland shrinkage as a result of atrophy/fibrosis has been described as a finding following androgen deprivation. This compromises the distinction of actual tumor margins 1-4.
The patient is intended for intensity-modulated radiotherapy.