A patient who developed pulmonary Langerhans' cell histiocytosis after chemotherapy for nodular sclerosing Hodgkin's disease is presented. Twenty-one cases of Langerhans' cell histiocytosis associated with Hodgkin's disease have been reported in the literature. Such an association seems to be more than fortuitous. The possibilities of a common etiological agent inducing both Hodgkin's disease and Langerhans' cell histiocytosis and of a reactive proliferation of Langerhans' cells after radiotherapy or chemotherapy for Hodgkin's disease are discussed.
