Vol. 93 No.10 October 2000
Origin of Laryngeal Carcinoma ; A Review and Immunohistological Observation
Tadashi Nakashima , Kiminori Satoh , Tetsuyoshi Umeno (Kurume University)
The larynx is subdivided
into three regions : supraglottic, glottic and subglottic. In neonates or
infants, the laryngeal mucosa is covered with respiratory epithelium except for
the vocal cord and the aryepiglottic fold. Most malignant neoplasms of the
larynx are squamous cell carcinomas.
In this study, we focused on the features
of the extension and the histopathologic findings of each type of laryngeal
carcinoma and reviewed literature regarding the origin of carcinogenesis.
Squamous cell carcinomas of glottic-type laryngeal carcinoma originate from
squamous epithelium of the vocal cord. Because of the early appearance of
hoarseness, glottic cancer is found at an early stage, and the prognosis is
generally good.
In
contrast, supraglottic and subglottic type laryngeal carcinomas show various
characteristics not only in their pattern of extension but also in the
histopatholgic findings. In particular, the so-called transglottic carcinoma
invades the laryngeal frameworks, and the prognosis is poor.
Carcinogenesis of the supraglottic
laryngeal carcinoma was thought to be highly correlated with squamous metaplasia
of the respiratory mucosa of the supraglottic larynx. Metaplasia is highly
associated with aging. Smoking habits as well as exposure to air pollution
accelerate squamous metaplasia of the mucosa. Even in mucosa of the ventricle,
where it is completely covered with ciliated glandular epithelium in neonates
and infants, metaplasia was found to occur in adult larynges.
Using immunohistochemical methods, we
also stained the glottic and so-called “ventricular carcinomas” using
antiserum as a marker. Expression of epithelial membrane antigens was
predominantly observed in glottic-type carcinomas. The expression of a secretory
component, produced locally in the cytoplasm of glandular cells, was intense in
most ventricle carcinomas. We believe that some carcinomas in the laryngeal
ventricle originate from cells of the secretory glandular acini or epithelium.