Histologic assessment of lymph nodes in mycosis fungoides/sézary syndrome (cutaneous T-cell lymphoma): Clinical correlations and prognostic import of a new classification system

Mycosis fungoides and the Sézary syndrome share common cutaneous histopathologic features, and this spectrum of malignant disease is referred to here as cutaneous T-cell lymphoma (CTCL). A method (LN classification) for describing the histopathologic features of lymph nodes in CTCL is presented. In this system, lymph node biopsy specimens are scored according to the number of atypical lymphoid cells in T-cell-dependent paracortical zones and the preservation or distortion of the lymph node architecture. Lymph node architecture is preserved in lymph nodes scored LN1 to LN3, and these nodes may have coexistent dermatopathic change. LN1 nodes have single infrequent atypical lymphocytes in paracortical T-cell regions. LN2 nodes have small clusters of paracortical atypical cells. LN3 nodes have large clusters of atypical cells. LN4 nodes are partially or totally effaced by atypical cells. This system was used to classify 96 lymph node biopsy specimens obtained within six months of the initial diagnosis of CTCL; no LN1 nodes, 37 LN2, 44 LN3, and 15 LN4 nodes were found. The LN class was significantly correlated with the extent of skin, blood, and visceral involvement, as well as with survival. Patients with LN2 lymph nodes have an estimated five-year survival of 70 per cent, while patients with LN3 and LN4 nodes have estimated five-year survivals of 30 and 15 per cent, respectively. The survival differences between the LN subgroups were all significant (P<0.05). The LN classification system was clearly shown to be reproducible among experienced pathologists. The LN system for the histopathologic classification of lymph nodes in CTCL is of prognostic value and should be used to assess lymph node biopsies in patients with CTCL.