A6.

TNMB stage system of Mycosis fungodies and Sézary syndrome

Stage	Clinical manifestations
Skin
T1	Localized patches, papules, and/or plaques, <10% body surface area
T2	Patches, papules, and/or plaques, ≥10% body surface area
T3	One or more lumps are formed (diameter ≥1 cm)
T4	Fusional erythema ≥80% body surface area
Lymph nodes
N0	No abnormal lymph nodes; no biopsy required
N1	Abnormal lymph nodes; histopathology shows Dutch level 1 or NCI LN 0−2
N2	Abnormal lymph nodes; histopathology shows Dutch level 2 or NCI LN 3
N3	Abnormal lymph nodes; histopathology shows Dutch level 3−4 or NCI LN 4
NX	Abnormal lymph nodes; no histological confirmation
Viscera
M0	No viscus involvement
M1	Visceral involvement (required pathological diagnosis and indication of the affected organs)
MX	Visceral abnormalities; no histological diagnosis
Blood
B0	No obvious blood involvement: atypical cells (Sézary cells) accounts for 5% of peripheral blood lymphocytes
B1	Low-load blood involvement: atypical cells (Sézary cells) accounts for >5% of peripheral blood lymphocytes, but do not reach B2 level
B2	High-load blood involvement: atypical cells (Sézary cells) ≥1,000/μL or CD4+/CD7− cell ratio ≥40% or CD4+/CD26− cell ratio ≥30%