Based on Olsen et al, Olsen et al, and Kim et al.^7-9 Changes or confirmation of staging are noted in bold in table above and in further description below. Options for characterizing clonality further by designation as A (clone negative or equivocal) and B (clone positive and identical to skin) are presented. If a clone in LN or viscera is detected but different from that identified in the skin, another concurrent lymphoproliferative process should be considered.

T₀ is used for clinical trials in order to track clearance of lesions in the skin compartment. No patient with PCL at time of diagnosis should be T_0.

Patients with both erythroderma and tumors may be designated as T₄(T₃).⁷ The BSA of 80% is used to define erythroderma in MF/SS at study entry, but any decrease in BSA during the study does not affect the entry classification.

Abnormal LNs are those now > 1.5 cm LDi according to the Lugano classification and confirmed by imaging. The pathological findings of a representative abnormal LN may apply to all abnormal lymph nodes.

Blood staging for MF/SS is defined currently as B₀ = <250/μL of CD4⁺/CD26⁻ or CD4⁺/CD7⁻ cells, B₁= does not meet criteria for B₀ or B_2, and B₂ = ≥1000/μL of CD4⁺/CD26⁻or CD4⁺/CD7⁻cells or other aberrant population of lymphocytes identified by flow cytometry. It is expected that patients with high blood tumor burden (B₂) will have a clone in the blood that is identical to that in the skin. Nonidentical T-cell clones are often detected in peripheral blood with increasing age and are of unknown clinical significance.

See Figure 2 for peripheral LN drainage areas of the body.