Scanning electron microscopy of vocal cord hyperplasia, keratosis, papillomatosis, dysplasia and carcinoma

Developing Classifications of Laryngeal Dysplasia: The Historical Basis

During the last 60 years numerous significant attempts have been made to achieve a widely acceptable terminology and histological grading for laryngeal squamous intraepithelial lesions. While dysplasia was included in the pathology of the uterine cervix already in 1953, the term dysplasia was accepted in laryngeal pathology first after the Toronto Centennial Conference on Laryngeal Cancer in 1974. In 1963 Kleinsasser proposed a three-tier classification, and in 1971 Kambic and Lenart proposed a four-tier classification. Since then, four editions of the World Health Organisation (WHO) classification have been proposed (1978, 1991, 2005 and 2017). Several terms such as squamous intraepithelial neoplasia (SIN) and laryngeal intraepithelial neoplasia (LIN) are now being abandoned and replaced by squamous intraepithelial lesions (SIL). The essential change between the 2005 and 2017 WHO classifications is the attempt to induce a simplification from a four- to a two-tier system. The current WHO classification (2017) thus recommends the use of a two-tier system with reasonably clear histopathological criteria for the two groups: low-grade and high-grade dysplasia. Problems with interobserver variability apart, subjectivities and uncertainties remain, but to a lesser degree. Ongoing and additional molecular studies may help to clarify underlying events that will increase our understanding and possibly can facilitate our attempts to obtain an even better classification. The classification needs to be easier for the general pathologist to perform and easier for the clinician to interpret. These two objectives are equally important to provide each patient the best personalised treatment available for squamous intraepithelial lesions.

Light and scanning electron microscopic investigation of the laryngeal mucosa of Syrian golden hamsters

The laryngeal epithelium of Syrian golden hamsters (SGH) at 8, 12.5 and 17 months was studied by scanning electron microscopy (SEM) and light microscopy (LM). Stratified squamous epithelium, covered with shallow microvilli or microplicae, was observed covering the upper two-thirds of the laryngeal epiglottis, the false folds, the vocal cords and the luminal protrusions of the arytenoid cartilages. Pseudostratified respiratory epithelium, characterized by mucus producing cells with microvilli and ciliated cells, covered the base of the epiglottis and the entire subglottis. Transitional zones between squamous and respiratory epithelium were composed of stratified cuboidal epithelium. Towards the base of the epiglottis cuboidal cells with a relatively large surface area were present which displayed short surface microvilli, while cells with a small surface area were covered with long microvilli. Age related changes were not observed. Degenerative changes of submucosal glands or cartilages occurred in almost every animal, but no epithelial lesions were found. The findings confirm a low incidence of spontaneous metaplasia in the laryngeal epithelium of the SGH.

The quiet revolution. Techniques of cell biology applied to tissue diagnosis

In the past decade many of the techniques of cell biology developed in the research laboratory have been applied to tissue diagnosis. Increasing use of electron microscopy has allowed ready differentiation of many neoplasms with an identical appearance under the light microscope. The identification of highly specific antigenic substances in individual cells using monoclonal antibodies in the immunoperoxidase technique has allowed a degree of diagnostic accuracy not previously available in tissue diagnosis. Recent efforts have been directed at more accurately predicting biological behavior on the basis of cellular characteristics. Techniques being introduced include morphometry (computer-assisted image analysis), cytophotometry (measurement of cellular DNA content), flow cytometry (analysis of cells in suspension for DNA content and other physical and chemical properties), scanning electron microscopy, and cytogenetics (the study of cellular chromosomes).

The role of scanning electron microscopy in the diagnosis of human laryngeal cancer

Malignant and non-malignant human laryngeal tissue samples (31 cases) were examined first by light microscopy (LM) and then the specimens were reprocessed for scanning electron microscopy (SEM). The presence of LM and SEM signs of malignancy were compared with each other. In all the 22 histologically unambiguous cases the LM and SEM results were in accordance with each other. From the 9 histologically doubtful cases, 2 were found malignant and 3 benign by retrospective SEM. The case histories of these 5 patients have confirmed the SEM results. This preliminary study suggests the application of SEM in histologically doubtful laryngeal biopsies.