[Ultrastructural basal lamina alterations at the tumor-stroma junction in invasive laryngeal carcinoma (author's transl)].

The tumor-stroma junction of invasive squamous cell carcinoma of the larynx was examined by electron microscopy. Ultrastructural alterations of the basal lamina and associated hemidesmosomes were observed. The basal lamina was very thin, discontinuous or absent from extensive areas of the junction. Some basal malignant keratinocytes exhibited deep dermal invaginations or multiple irregularly shaped infoldings of the plasma membrane which were studded with hemidesmosomes and were covered by a basal lamina. Other structural changes were the occurrence of a basal lamina on lateral cell surfaces in the intercellular space between adjacent malignant keratinocytes. These results are discussed in connection with the possible barrier function of the basal lamina during tumor invasion of the underlying stroma. The observations indicate that disruption of the basal lamina should not be regarded as an ultrastructural criterion for tumor invasion in laryngeal carcinoma.