Prognostic value of the histologic classification of peripheral T-cell lymphoma: a clinico-pathologic study of 71 HTLV-1 negative cases.

The histologic and clinical features of 71 cases of peripheral T-cell lymphoma (PTCL) have been studied. All patients were HTLV-1 negative. The T-cell phenotype was demonstrated by immunohistochemistry on cryostat sections (41 cases) and paraffin-embedded sections (30 cases). All cases were histologically classified according to the updated Kiel classification of non-Hodgkin's lymphoma (low and high-grade) and according to a Working Formulation (WF)-based classification (predominantly small cells, mixed small and large cells, and predominantly large cells). Most cases were in the high-grade group according to both classifications. The prognostic value of these two classifications was comparatively assessed. The analysis of the actuarial survival curves showed that, by using the updated Kiel classification, low-grade PTCL had a survival probability higher than high-grade PTCL although the difference was not statistically significant. Similar results were obtained when the WF-based classification was applied: furthermore, actuarial survival curves of mixed small and large cell PTCL, and of large cell PTCL were rather similar, thus indicating that differentiating these two categories has a limited prognostic value.