Inflammatory bowel disease in pediatric and adolescent patients: A biomolecular and histopathological review

Table 1 Montreal and Paris classifications for Crohn’s disease

	Montreal classification		Paris classification
Age at diagnosis	A1	< 17 yr	A1a	< 10 yr
			A1b	10-16 yr
	A2	17-40 yr	A2	17-40 yr
	A3	> 40 yr	A3	> 40 yr
Location	L1	Ileal disease	L1	Distal 1/3 ileum ± limited cecal disease colonic disease ileocolonic disease isolated
	L2	Colonic disease	L2	upper disease
	L3	Ileocolonic disease	L3
	L4	Isolated upper disease	L4
			L4a	Upper disease proximal to ligament of Treitz
			L4b	Upper disease distal to ligament of Treitz and proximal to distal 1/3 ileum
Behavior	B1	Non-stricturing, non-penetrating	B1	Non-stricturing, non-penetrating
	B2	Stricturing	B2	Stricturing
	B3	Penetrating	B3	Penetrating
			B2B3	both stricturing and penetrating
	P	Perianal disease modifier	P	Perianal disease modifier
Growth	Not applicable		G0	No evidence of growth delay
			G1	Growth delay