| T (skin) |
| T1 |
Limited patch/plaque/papules (< 10 percent of total skin surface) |
| T2 |
Generalized patch/plaque/papules (>10 percent of total skin surface) |
| T3 |
Tumors (≥ 1 cm diameter) |
| T4 |
Generalized erythroderma (confluence of erythema covering ≥ 80 percent body surface area) |
| N (nodes) |
| N0 |
Lymph nodes clinically ≤1.5 cm (biopsy not required) |
| N1 |
Lymph nodes enlarged clinically, but not involved by histology (includes "reactive" and "dermatopathic" nodes) |
| N2 |
Lymph nodes enlarged clinically and abnormal cells are present on histology but they do not efface the nodal architecture. |
| N3 |
Lymph nodes enlarged clinically. On histology, there is partial or complete effacement of the nodal architecture by abnormal cells. |
| M (viscera) |
| M0 |
No visceral involvement |
| M1 |
Visceral involvement (histologically confirmed) |
| B (blood) |
| B0 |
No circulating atypical (Sezary) cells (<5 percent of lymphocytes) |
| B1 |
Circulating atypical (Sezary) cells (≥5 percent of lymphocytes) |
| B2 |
High blood tumor burden: ≥1000/microL Sezary cells with positive clone |
Note: Sézary cells are atypical mononuclear cells with cerebriform nuclei. Their presence in more than 5% in peripheral circulation is used for diagnostic criterion of Sézary’s
Syndrome (SS). SS is a leukemic variant of the disease, which, generally, is manifested since its start with erythroderma and goes through usually with diffuse alopecia,
palmo-plantar hyperkeratosis and diffuse lymph node access. Patients suffering from SS have worse prognosis.