[Poorly differentiated laryngeal tumors. An electron microscopy analysis]

Poorly differentiated laryngeal carcinomas, which light microscopically are made up of anisomorphic nuclei, undifferentiated cytoplasm and hardly visible cell membranes, show electronmicroscopically a remarquable polymorphism. The tumor cells, which form solid or trabecular groups of different sizes often with poorly defined borderlines to the stroma, are subdivided according to their ultrastructural features in spinosa, secretory and stemcell types. Lymphocytes, plasmacells and reticular cells may show distinct focal proliferation or may be completely absent. In some cases, there was a transition between tumour tissue and metaplastic ciliated and glandular epithelium with concomitant reduction of normal glands. By comparison, besides hyperplastic and metaplastic squamous and ciliated epithelium, normal mucosal biopsies reveal invaginations of pseudostratified ciliated epithelium.