Scar carcinomas of the lung in a histoplasmosis endemic area.

Seventeen cases of pulmonary scar carcinomas were found in 112 surgically resected pulmonary carcinomas from 1985 through 1988 in a hospital situated in a histoplasmosis endemic area. These carcinomas can be divided into two types: Type I, mucinous; and Type II, non-mucinous (Clara cell). Each type of carcinoma constitutes a discrete group in reference to gross features, histologic and ultrastructural cell types, and the nature of the scar. The scar in Type I carcinomas appears mostly desmoplastic. The majority of Type II carcinomas appear to have arisen around a preexisting histoplasmosis granuloma which contains yeast organisms on microscopic examination. Pulmonary scar carcinoma is not a single discrete clinicopathologic entity. It appears that peripheral carcinomas of different histogenesis are incorporated in this category.