Snapshot A 55-year-old man complains of a rash he has had for many months. It occasionally itches. While he has tried some topical over-the-counter steroids, he has not seen his dermatologist yet since the symptoms were mild. On physical exam, his legs are covered with multiple well-demarcated red papules and plaques with some telangiectasias. A skin biopsy is obtained. A week later, the biopsy comes back with Pautrier microabsecesses, lymphocytic infiltrate, and cells with cerebriform nuclei. Introduction Both are variants of cutaneous T-cell lymphoma (CTCL) helper CD4+ T-cell lymphoma of the skin Mycosis fungoides (50-70% of CTCLs) skin involvement only Sézary syndrome (1-3% of CTCLs) leukemic form of CTCL CTCL + malignant T-cells in the blood Epidemiology older patients (median age 55-60) more common in male patients more common in black patients Presentation Symptoms generalized pruritus Physical exam mycosis fungoides well-demarcated, erythematous pruritic patches and plaques in non-sun-exposed areas can have telangiectasias and ulceration erythroderma (> 90% body involvement) early lesions may be confused with atopic dermatitis or psoriasis Sézary syndrome severely pruritic erythroderma with scaling alopecia lymphadenopathy hepatosplenomegaly Evaluation Physical exam to assess for lymphadenopathy and organomegaly Diagnosis usually made by clinical exam and history Diagnosis confirmed with skin biopsy lymphocytic infiltrate with Pautrier microabscesses within thickened epidermis. “buttock cells”: atypical lymphocytes with cerebriform nuclei (Sézary cells) Labs complete blood count with peripheral blood smear to look for Sézary cells (atypical T-cells) Differential Diagnosis Adult T-cell leukemia-lymphoma (ATLL) Atopic dermatitis Psoriasis Drug eruption (SJS) Treatment Pharmacologic options topical steroids topical chemotherapies radiation therapy interferon Prognosis, Prevention, and Complications Prognosis stage-dependent mycosis fungoides typically indolent slow-growing Sézary syndrome typically aggressive can be fatal Complications intense pruritus secondary cutaneous bacterial or viral infection