INVOLUCRIN IN LUNG-TUMORS - A SPECIFIC MARKER FOR SQUAMOUS DIFFERENTIATION

  • 1 January 1983
    • journal article
    • research article
    • Vol. 49  (5) , 563-568
Abstract
Involucrin is a precursor of the cross-linked envelope protein or marginal band present in human stratum corneum. This study uses immunohistochemical techniques for localizaiton of involucrin in histologic sections from 91 lung tumors to evaluate the usefulness of involucrin as a tumor marker in lung neoplasms. Although involucrin is absent from normal bronchial epithelium, it is expressed in cultured tracheal epithelial cell colonies and in bronchial mucosa with squamous metaplasia. Involucrin was present in all 25 cases of squamous and adenosquamous carcinoma. Staining was focal in 12 cases of squamous cell carcinoma and was most marked in the larger neoplastic cells in the center of squamous cell nests. Only 2 of 20 cases of adenocarcinoma revealed focal staining for involucrin, and these cases may represent adenosquamous variants. Six of 12 cases of large cell undifferentiated carcinoma stained for involucrin, indicating squamous differentiation, and 7 cases of malignant mesothelioma were negative. Isolated involucrin-positive cells were present in 2 of 16 cases of small cell anaplastic carcinoma and 1 of 11 carcinoid tumors, identifying variants of neuroendocrine tumors with dual differentiation. Patterns of localization of involucrin in paraffin and frozen sections were compared with staining for cytokeratins in parallel sections. Immunohistochemical localization of involucrin comprises a specific marker for squamous differentiation in lung tumors.