Basement membrane components in normal, dysplastic, neoplastic laryngeal tissue and metastatic lymph nodes

The immunohistochemical localization of the basement membrane (BM) components laminin, type IV collagen and fibronectin was analyzed in normal, dysplastic and neoplastic laryngeal specimens. The distribution of these macromolecules was also investigated in metastatic lymph nodes. A regular and continuous staining for laminin and type IV collagen was present in normal and mild dysplastic epithelium (LIN I); interruptions and reduplications were more evident in severe dysplasia (LIN III), together with an increased positivity for fibronectin in the subepithelial connective tissue. In squamous cell carcinomas the distribution of BM components was related to the degree of cellular differentiation, with a decreased immunostaining being evident in moderately and poorly differentiated carcinomas. Furthermore, the positivity for laminin and type IV collagen was influenced by the pattern of neoplastic growth, being continuous around the "pushing" border and discontinuous where the neoplastic front had an "invading" appearance. Similar changes were present in cervical metastatic lymph nodes. These observations tend to support the theory that the neoplastic growth is a cyclic process, with BM component synthesis and reabsorbtion related to the shifts of cellular metabolism.