Erythroderma: psoriasis or lymphoma? A diagnostic challenge and therapeutic pitfall

Psoriasis and lymphoma risk is widely debated, but few is known about misdiagnosis risk between erythrodermic psoriasis and lymphoma. In fact, erythroderma might represent a clinical presentation of psoriasis, cutaneous T-cell lymphomas and skin dissemination of systemic lymphomas.

All patients referred to psoriasis outpatient service with a diagnosis of erythrodermic psoriasis were re-examined. Among them, all the patients with a subsequent lymphoma diagnosis were included. For each patient data concerning age, gender, age at erythroderma onset, age at lymphoma diagnosis, immune-suppressive therapy, type of lymphoma and relative stage, lymphoma treatment and outcome were obtained.

Twenty-five patients (15 females and 10 males) with a diagnosis of erythrodermic psoriasis were retrieved. Among them, 9 patients (5 males and 4 females) were affected by erythrodermic lymphoma, including 4 patients with Sèzary Syndrome, 3 with mycosis fungoides, and 2 with peripheral T-cell lymphoma not otherwise specified. Prior to lymphoma diagnosis all the patients (9/9) received cyclosporine, two (2/9) of them methotrexate, one (1/9) azatioprine, and two (2/9) systemic corticosteroids. The prognosis of our patients was poor, due to immune-suppressive drugs administration in patients with undiagnosed lymphoma. The only exception was one (1/9) patient with Sèzary Syndrome still alive with disease after 120 months of follow-up.

In case of patients with erythroderma, multiple skin biopsies and specific peripheral blood studies like flow cytometry and T-cell receptor gene rearrangement analysis are required in order to avoid misdiagnosis risk between psoriasis and lymphoma.