Langerhans cells (LC) (CD1a-positive dendritic epidermal cells) have been proposed to favour the pathogenesis of mycosis fungoides (MF) and Sézary syndrome (SS). We therefore examined the influence of LC retrospectively on the survival of 35 patients. Two clinical parameters (age, stage of disease) were additionally evaluated. LC densities were morphometrically assessed on immunohistochemically stained cryostat sections of the respective diagnostic specimen. Death resulting from MF and SS was significantly (p = 0.003) less frequent in patients with CD1a-positive epidermal cell densities higher than 90 cells/mm2 (optimal break point) as compared with patients with lower numbers, independently of the stage of disease. This result suggests that LC have a significant impact on the prognosis of patients with MF and SS, playing an important role in the host defense mechanisms against these lymphomas.
