An assessment of involucrin as a diagnostically useful immunohistochemical marker in lung tumours.

ABSTRACT

A previous report has described involucrin as a specific immunohistochemical marker of squamous differentiation in lung carcinomas. The aim of our study was to examine the expression of this antigen in a wide variety of lung tumours, with particular attention to its potential value in the typing of biopsy specimens. We found that immunostaining for involucrin was common in squamous carcinomas but was also found in adenocarcinomas, adenosquamous carcinomas, large cell carcinomas and carcinosarcomas. Small cell carcinomas, carcinoid tumours and mesotheliomas were negative. Contrary to previous claims, this marker appears to have little diagnostic utility in the typing of lung tumours.