[Severe late stage lesions of pulmonary histiocytosis X. Report of 3 transplantations].

The anatomical lesions of three subjects suffering from pulmonary histiocytosis X and treated with lung transplantation were studied in order to detail the changes occurring in late stages of the disease; the early stages are known on account of lung biopsies done with a diagnostic aim. All the subjects were, at the time of transplantation, in a precarious clinical state and were practically bed-bound as a result of their dyspnoea with a history of histiocytosis X which had been known for 9, 7 and 3 years respectively; one patient had a cardiopulmonary bypass and two unilateral lung transplant. The results of the histological study produced data which was slightly discordant from the communly held ideas; the de Langerhans cells persist in large numbers and after many years of the evolution of the disease, even though other elements of the granuloma have practically disappeared. Fibrosis is absent playing no role in the genesis of the respiratory failure. The lesions are destructive, leading to a disappearance of the alveolar capillary bed which is the source of the dyspnea. The honeycomb cavities to the destroyed lung are varied in nature: most correspond to the disappearance of the dividing walls of the alveoli or the pulmonary acinus, some others related to dilated terminal bronchioles and finally others to hollowed out granulomas which have become cavities. The peculiar characteristic of the lung allows for destructive cavities to be produced by the airflow, submitted to a process of auto-aggravation by the elastic forces and the tension of the pulmonary parenchyma.