A histo‐immunopathologic and prognostic study of erythrodermic cutaneous T‐cell lymphoma

BACKGROUND: Sezary syndrome (SS) and erythrodermic mycosis fungoides (E-MF) represent two expressions of erythrodermic cutaneous T-cell lymphoma (E-CTCL). METHODS: Histopathologic features were compared on skin specimens from 41 patients with SS and 70 patients with E-MF. Immunopathologic findings were compared on 42 SS and 79 E-MF specimens. RESULTS: Specimens of SS usually showed band-like dermal infiltrates with intermediate-sized lymphoid cells and few plasma cells; on the other hand E-MF more often had a perivascular infiltrative pattern, predominance of small/mixed lymphoid cells and eosinophils. SS also had lower numbers of CD8+ cells and higher numbers of CD62L+ cells compared to E-MF. For E-MF patients, the presence of large Pautrier collections, infiltrates with intermediate-sized cells, increased number of mitotic figures and >/=50% CD62L+ cells in the dermal infiltrate correlated with a relatively poor disease-specific survival. However, only the presence of mitotic figures retained prognostic significance with clinical stage as a covariate. CONCLUSIONS: Clinical stage provides the most important prognostic information for patients with E-CTCL. However, mitotic activity for E-MF and CD8+ cells <20% for SS have additional value. We hypothesize that observed differences in plasma cell and eosinophil numbers may reflect the influence of CD62L+ central memory T-cells in the microenvironment.