Elastosis in lung carcinoma: Immunohistochemical, ultrastructural and clinical studies

Elastosis is the pathological finding of focal deposits of elastic fibers i n abnormal amounts within tissue. It is well described in the case of infil trating carcinoma of the breast, but elastosis in lung carcinoma has not be en previously documented in detail. We investigated the characteristics of elastosis in lung carcinoma with light and electron microscopies, and immun ohistochemistry for alpha-1-antitrypsin. A total of 184 surgically resected primary lung carcinomas were studied. Elastosis was detected in adenocarci nomas (85/106), squamous cell carcinomas (11/60) and adenosquamous carcinom as (5/7), but not in small-cell carcinomas (n = 4) or large-cell carcinomas (n = 5). The degree of elastosis in each case was divided into one of five grades, graded as 3+ to 1-. The score of elastosis was significantly highe r in adenocarcinoma than that in squamous-cell carcinoma (P < 0.01). In the cases of adenocarcinoma, the mean score of elastosis in the well-different iated type (WD n = 43) was higher than that in the moderately differentiate d (MD) (n = 39; P = 0.012) and poorly differentiated (PD) types (n = 24; P < 0.01). The mean score of elastosis in MD adenocarcinoma was also higher t han that in the PD type (P < 0.01). Light- and electron-microscopic analyse s revealed that these elastic fibers in elastosis were composed of aggregat es of thick mature and fine immature elastic fibers, and were positive for alpha-1-antitrypsin. It is suggested that both degraded elastic fibers and newly synthesized fibers are contained in the elastosis of lung carcinoma. Although no significant evidence was detected to suggest any correlation be tween elastosis and the degree of tumor invasion, the survival curves of ad enocarcinomas with elastosis showed a significantly improved prognosis than of those without elastosis in the cases of stages IA and IB (n = 52; P = 0 .026).