Background: Erythroderma may result from different causes, but a proportion remains undetermined (idiopathic erythroderma). Patients with idiopathic erythroderma have often been regarded to have a pre-Sézary syndrome because some of these patients have developed a cutaneous T-cell lymphoma during follow-up.

Objective: The aim of this study was to investigate if this was true for our group and also if it is possible to identify further which patients are at high risk of developing cutaneous T-cell lymphoma.

Methods: We analyzed clinical and follow-up data and reviewed the skin histopathology of all patients who were diagnosed with idiopathic erythroderma in our clinic between 1977 and 1994.

Results: Twenty-eight patients, 16 males and 12 females, were diagnosed with idiopathic erythroderma. This is 27% of the patients who were diagnosed with erythroderma in our clinic, during this period. During the median follow-up of 33 months, 35% of the patients went into complete remission and 52% showed partial remission. Three patients (13%), all females, had persistent chronic erythroderma. Two of the latter group progressed to cutaneous T-cell lymphoma, i.e. 1 to Sézary syndrome and 1 to mycosis fungoides.

Conclusions: Based on our results we conclude that only patients with persistent chronic idiopathic erythroderma, which is a minority, have an increased risk of developing cutaneous T-cell lymphoma and therefore need a close and long-term follow-up.