A1.

T stage

T stage	Thickness	Ulceration status
TX: Primary tumor thickness cannot be assessed (e.g., diagnosis by curettage)	Not applicable	Not applicable
T0: No evidence of primary tumor (e.g., unknown primary or completely regressed melanoma)	Not applicable	Not applicable
Tis (melanoma in situ )	Not applicable	Not applicable
T1	≤1.0 mm	Unknown or unspecified
T1a	<0.8 mm	Without ulceration
T1b	<0.8 mm	With ulceration
	0.8−1.0 mm	With or without ulceration
T2	>1.0−2.0 mm	Unknown or unspecified
T2a	>1.0−2.0 mm	Without ulceration
T2b	>1.0−2.0 mm	With ulceration
T3	>2.0−4.0 mm	Unknown or unspecified
T3a	>2.0−4.0 mm	Without ulceration
T3b	>2.0−4.0 mm	With ulceration
T4	>4.0 mm	Unknown or unspecified
T4a	>4.0 mm	Without ulceration
T4b	>4.0 mm	With ulceration