Table 2.

Definitions of pathological variables used in the Oxford classification

Variable	Definition		Score
Mesangial hypercellularity	<4	Mesangial cells/mesangial area = 0	M0 ≤ 0.5
	4–5	Mesangial cells/mesangial area = 1	M1 > 0.5a
	6–7	Mesangial cells/mesangial area = 2
	≧8	Mesangial cells/mesangial area = 3
		The mesangial hypercellularity score is the mean score for all glomeruli
Segmental glomerulosclerosis	Any amount of the tuft involved in sclerosis, but not involving the whole tuft or the presence of an adhesion		S0—absent
			S1—present
Endocapillary hypercellularity	Hypercellularity due to increased number of cells within glomerular capillary lumina causing narrowing of the lumina		E0—absent
			E1—present
Tubular atrophy/interstitial fibrosis	Percentage of cortical area involved by the tubular atrophy or interstitial fibrosis, whichever is greater		T0—0–25 %
			T1—26–50 %
			T2—>50 %

^aMesangial score should be assessed in periodic acid-Schiff-stained sections. If more than half the glomeruli have more than three cells in a mesangial area, this is categorized as M1. Therefore, a formal mesangial cell count is not always necessary to derive the mesangial score