## Gleason Grading System for Prostate Cancer **Key Point:** The Gleason score is the sum of the primary (most common) and secondary (second most common) histological patterns, each graded 1–5, giving a total score of 2–10. ### Gleason Pattern Scoring | Grade | Pattern Description | | --- | --- | | 1 | Uniform, small glands; well circumscribed | | 2 | Uniform glands with slight variation; minimal infiltration | | 3 | Varied gland size and shape; infiltrative borders | | 4 | Fused or cribriform glands; poorly differentiated | | 5 | Solid sheets or single cells; no glandular formation | **High-Yield:** Gleason score = Primary pattern + Secondary pattern. For example, if the most common pattern is grade 3 and the second most common is grade 4, the Gleason score is 3 + 4 = 7. **Mnemonic:** **GLANDS** = **G**rading based on **L**umen **A**rrangement **N**uclear variation **D**ifferentiation **S**tructure (helps recall that Gleason evaluates glandular architecture, not just nuclear features). ### Prognostic Significance - **Gleason score 2–6:** Low risk; better prognosis - **Gleason score 7:** Intermediate risk; heterogeneous outcomes - **Gleason score 8–10:** High risk; poor prognosis **Clinical Pearl:** In contemporary practice, Gleason scores of 2–5 are rarely assigned because they are associated with excellent prognosis and may lead to undertreatment. The modern grading system emphasizes scores ≥6.
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