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Montreal classification for Crohn’s disease phenotype
| Age at diagnosis (A) | Location of disease (L) | Behavior of disease (B) |
|---|---|---|
|
A1: ≤16 years A2: 17–40 years A3: >40 years |
L1: ileal L2: colonic L3: ileocolonic L4: modifier for upper gastrointestinal tract |
B1: non-stricturing/nonpenetrating B2: stricturing B3: penetrating p: modifier for perianal disease |
