What is the “erased charcoal sign”?
It refers to a homogeneously T2 low-signal appearance of a lesion in the prostatic transition zone with blurred, smudged margins.
What is the percentage of prostate cancers that originate in the transition zone?
Approximately 20-30% of prostate cancers originate in the transition zone.
Are there imaging signs of extraprostatic extension?
There is a broad capsular contact (≥10 mm) and bulging of the left anterolateral contour with irregular margins and capsular breach.
Findings:
Quality: mild geometric distortion on DWI, does not compromise diagnostic confidence
Prostate size: 40 x 32 x 41 mm (CC x AP x ML) ≈27 mL, PSA density ~0.42 ng/mL2.
Haemorrhage: none
Peripheral zone (PZ): heterogeneously slightly, decreased signal, linear/wedge-shaped hypointensities
Transition zone (TZ): moderate heterogeneity, focal finding as below:
Focal lesion #1:
- location: left mid gland anterior transition zone from (TZa) extending to the right and from apical to basal
- lesion size: 21 x 13 x16 mm
- T2w: circumscribed homogeneous, hypointense: “erased charcoal sign”, with capsular contact and bulge anteriorly - category 5/5
- DWI: focal slightly hyperintense on DWI (b1000) and markedly hypointense on ADC - category 3/5
- DCE: focal early enhancement - positive
Prostate margin: capsular contact, bulge and breach of the left anterior margin
Overall PI-RADS category: 5
Seminal vesicles: not involved
Lymph nodes: enlarged lymph node adjacent to the left internal iliac vessels (~11 mm), the round suspicious lesion (~6 mm) in the preprostatic fat tissue
Pelvic bones: no osseous metastases
Other pelvic organs: right bladder diverticulum
Impression:
A very highly suspicious lesion in the left anterior transition zone (TZa) and anterior fibromuscular stroma (AFS) with extraprostatic extension.
Highly suspicious lymph nodes in the left iliac fossa and in the preprostatic fat tissue.
MRI putative stage cT3a - PI-RADS 5
A prostate biopsy was recommended.