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What is Sézary-Lutzner cells are seen in and explain in detail?
Cutaneous T cell lymphoma (CTCL) represents a spectrum of lymphoproliferative disorders affecting the skin. Two different clinical types of malignant T-cell disorders were originally recognized: mycosis fungoides, a chronic proliferative process; and a more aggressive nodular eruptive variant, mycosis fungoides d'emblée. Lesions of mycosis fungoides usually involve truncal areas and include scaly, red -brown patches; raised, scaling plaques that may even be confused with psoriasis; and fungating nodules. In some individuals, seeding of the blood by malignant T cells is accompanied by diffuse erythema and scaling of the entire body surface (erythroderma), a condition known as Sézary syndrome. The histologic hallmark of CTCL of the mycosis fungoides type is the presence of the Sézary-Lutzner cells. These are T-helper cells (CD4+) that characteristically form band-like aggregates within the superficial dermis ( Fig. 25-19B ) and invade the epidermis as single cells and small clusters (Pautrier microabscesses). These cells have markedly in folded nuclear membranes, imparting a hyperconvoluted or cerebriform contour. Although patches and plaques show pronounced epidermal infiltration by Sézary-Lutzner cells (epidermotropism), in more advanced nodular lesions the malignant T cells often lose this epidermotropic tendency, grow deeply into the dermis, and eventually spread systemically.