🔬 Gleason Score & Grade Group Risk Simulator

Biopsy Slide Loaded — Scanning the Tissue

A stained biopsy core sits ready under the scope.

• 10–12: Core count (systematic needle biopsy)
• H&E: Stain used (hematoxylin and eosin)
• 4 µm: Section thickness (paraffin-embedded slice)
• 4–10x: Read magnification (low-to-medium power)

What the pathologist looks for

Glandular architecture, not single-cell detail, drives the grade.

Why architecture over cytology

Pattern arrangement proved more reproducible than nuclear grading.

Architecture-first grading has held up for nearly 60 years.

Primary Pattern Identified — The Dominant Architecture

Drag the primary slider — the majority pattern fills the field.

• >50%: Primary definition (most prevalent pattern)
• Round glands: Grade 3 look (discrete, single lumen)
• Fused glands: Grade 4 look (cribriform, glomeruloid)
• No glands: Grade 5 look (solid sheets, cords)

Spotting the majority pattern

Scan the whole core, estimate area covered by each pattern.

Grade 3 vs 4 vs 5 cues

Lumen loss and fusion mark the jump from 3 to 4 to 5.

Watch the tissue view redraw as you move the slider.

Secondary Pattern Identified — The Minority Architecture

The wedge region marks the second most common pattern.

• 2nd most: Secondary definition (next largest area)
• Grade 3: Reported floor (lowest grade used today)
• ~28%: Field split shown (wedge vs majority field)
• 3–5 scale: Both graded (same criteria as primary)

Same criteria, smaller area

Secondary pattern uses identical architectural cues, less tissue.

Single-pattern tumors

If only one pattern exists, it is simply doubled.

A pure grade-3 tumor is scored 3+3, not just 3.

Gleason Sum Calculated — Primary Plus Secondary

Primary grade and secondary grade are simply added together.

• P + S: Formula (primary plus secondary)
• 6–10: Reported range (contemporary biopsy practice)
• Both = 7: 3+4 vs 4+3 (but not the same disease)
• Yes: Order matters (first number is dominant)

Order encodes dominance

The first number is always the more prevalent pattern.

Why the sum can mislead

Same sum, different dominant pattern, different behavior.

4+3 behaves worse than 3+4 despite an identical sum.

Grade Group Assigned — The Modern Reporting Standard

The Gleason sum now maps onto one of five Grade Groups.

• Sum 6: Grade Group 1 (3+3, lowest risk)
• 3+4=7: Grade Group 2 (primary well-formed)
• 4+3=7: Grade Group 3 (primary fused/cribriform)
• 8 / 9–10: Grade Group 4/5 (highest-risk architecture)

Five groups, five outcomes

ISUP 2014 split sums into five clearly separated categories.

Why grouping replaced raw sums

Grade Group separates 3+4 from 4+3 cleanly.

Grade Group is now the standard label on pathology reports.