Introduction

Langerhans cell histiocytosis (LCH) may affect patients of any age, from the newborn to the elderly (Nezelof et al., 1979; Aricò and Egeler, 1998; Aricò et al., 2003). For several reasons this disease has been more familiar to pediatricians than to specialists of adult patients, and in adults the features of this disease are still poorly defined. Thus, most of the available information concerning clinical features, pathogenesis, and treatment outcome derives from the pediatric experience. Several features of the disease are common to pediatric and adult patients who may both have either localized or disseminated disease. The proportion of cases with lung involvement is much higher in adults, however. This can be partly explained by cigarette smoking, but other differences between pediatric and adult LCH still require elucidation.

Background and clinical features

Only a limited number of literature reports are available which describe series of patients with LCH diagnosed during adulthood, and only a few describe relatively large series of patients. Furthermore, most of these reports derive from single-specialty experiences, which may carry an inherent selection bias. In addition, continued uncertainty with regard to the pathogenesis of adult LCH has limited our current ability to devise optimal therapy, and no randomized clinical trials have been conducted in adults so far. Thus, most information derives from the descriptions of single or a few cases, often reported retrospectively. Forty years ago, Lewis reported 12 patients with ‘eosinophilic granuloma and its variants with special reference to lung involvement’ (Lewis, 1964).