Table 1.

The microscopic features with descriptions for each grade (WHO73/ 04)

	WHO73			WHO04
	Grade 1	Grade 2	Grade 3	Low grade	High grade
Architecture
Papillae	Delicate	Varies	Broad, varies	Slender	Broad
Superficial layer (umbrella cell layer)	Usually present	Usually present	Partially or completely lost	Usually present	Partially or completely lost
Papillary fusion	Some	Varies	Common	Some	Varies
Nuclear arrangement
Polarity	Preserved	Moderate loss	Lost	Preserved, moderate loss	Lost
Maturation	Normal	Some	Lost	Preserved, moderate loss	Lost
Cohesion	Normal	Some	Lost	Some	Lost
Proliferation
Mitotic figures	Rare, basal	Lower half	Common, atypical	Rare	Common
Nuclear atypia
Nuclear enlargement	Mild	Mild	Varies	Mild	Varies
Nuclear shape	Uniform	Moderate variation	Pleomorphic	Moderate variation	Pleomorphic
Nuclear hyperchromasia	Mild	Moderate	Varies	Mild to moderate	Varies
Chromatin pattern	Finely granular	Granular	Coarse	Fine	Coarse
Nucleoli	Occasional	Occasional	Common	Occasional	Common
Giant nuclei	No	No	Yes	No	Yes