Cutaneous T-Cell Lymphoma: Mycosis Fungoides and Sézary Syndrome

Overview / Definition Cutaneous T-Cell Lymphoma (CTCL) is a heterogeneous group of lymphoproliferative disorders that primarily manifest in the skin. The most common forms of CTCL are Mycosis Fungoides (MF) and Sézary Syndrome (SS). MF typically presents as patches or plaques, while SS is characterized by erythroderma, lymphadenopathy, and circulating malignant T-cells. Epidemiology CTCL is relatively rare, with an estimated incidence of 0.2 to 0.5 per 100,000 person-years. The following points highlight its epidemiological features: MF is the most common form, accounting for approximately 50% of all CTCL cases. SS is less common, with an incidence of about 1 to 3 cases per million per year. There is a male predominance, particularly in MF, with a ratio of approximately 2:1. CTCL typically occurs in adults, with the majority of patients diagnosed between the ages of 50 and 70. Pathophysiology / Mechanism The pathogenesis of CTCL involves the clonal proliferation of malignant T-lymphocytes, primarily of the CD4+ subtype. Key mechanisms include: Initial skin colonization by malignant T-cells leading to localized skin lesions. Progression to more extensive skin involvement and potential systemic dissemination. Genetic mutations and chromosomal abnormalities, particularly in the JAK/STAT signaling pathway. Immune dysregulation, which may play a role in disease progression and response to therapy. Clinical Presentation The clinical manifestations of CTCL can vary significantly: Mycosis Fungoides: Initial presentation as asymptomatic patches that may resemble eczema or psoriasis. Progression to plaques and tumors, often with pruritus. Skin lesions may exhibit a characteristic "brisk" edge and can become ulcerated. Sézary Syndrome: Presentation with erythroderma covering >80% of the body surface area. Associated with lymphadenopathy and circulating atypical T-cells (Sézary cells). Patients may experience severe pruritus and systemic symptoms. Diagnosis / Workup Diagnosis o