Staging reference

Nodal Staging: Know the Boundary

A visual guide to regional and nonregional lymph nodes in prostate cancer

Where N1 Ends and M1a Begins

Explore the major nodal stations relevant to prostate cancer staging.

Hover over a nodal station to explore it.Tap a nodal station to explore it.

N0

No regional nodal metastasis

No suspicious regional nodes identified.

N1

Regional pelvic lymph-node metastasis

One or more regional nodes. Number and laterality do not change the N category.

Regional nodal stations
  • External iliac
  • Internal iliac
  • Obturator
  • Presacral / sacral
  • Periprostatic
M1a

Nonregional lymph-node metastasis

Examples of nonregional nodes
  • Common iliac
  • Para-aortic / retroperitoneal
  • Inguinal
Labeled frontal illustration of the pelvic and lower abdominal lymph node stations relevant to prostate cancer staging
RegionalN1 if metastatic
NonregionalM1a if metastatic

Find Them on MRI

Scrub through the pelvis to connect the nodal map with axial MRI anatomy.

When Is a Node Suspicious?

Size

Nodal size is useful but imperfect. A short-axis diameter greater than approximately 8 mm is suspicious, but metastatic nodes may be normal-sized.

Morphology
Round Irregular contour Loss of fatty hilum Heterogeneous / abnormal appearance
Limitation of MRI

Conventional MRI relies on size and morphology and has limited sensitivity for small-volume nodal metastatic disease. A negative conventional MRI does not exclude microscopic nodal metastases.

Report What Matters

Name the station. Measure the short axis. State the nodal station and staging implication.

Suspicious regional node N1
Suspicious nonregional node M1a

Sources

  1. American College of Radiology, European Society of Urogenital Radiology, AdMeTech Foundation. PI-RADS: Prostate Imaging Reporting and Data System, Version 2.1. 2019.
  2. Brierley JD, Gospodarowicz MK, Wittekind C, eds. TNM Classification of Malignant Tumours, 8th Edition (UICC). Prostate chapter, AJCC Cancer Staging Manual, 8th Edition.
  3. European Association of Urology (EAU). Prostate Cancer Guidelines.