Pulmonary histiocytosis X and carcinoma.

Four patients who developed both pulmonary histiocytosis X and carcinoma of the lung are described. Some authors have hypothesized that patients with pulmonary histiocytosis X-associated scarring are also at increased risk of developing lung carcinoma. However, case reports of this phenomenon are rare. The cases presently reported may support this hypothesis, although additional factors, such as cigarette smoking, may better explain the association.