Ultrastructural study of a postinflammatory "tumor" of the lung.

A typical postinflammatory "tumor" of the lung was resected from an asymptomatic 22-year-old white woman. Light and electron microscopic studies showed the lesion to be composed of metaplastic pneumonocytes, proliferated stroma, and chronic inflammatory cells. These findings confirm the inflammatory nature of the lesion and serve to distinguish this lesion from the neoplastic pulmonary sclerosing hemangioma.