Pathological Anatomy of Invasive Squamous Carcinoma

Abstract

Papers in the literature dealing with the pathology of squamous carcinoma of the larynx have exhibited a curiously lopsided emphasis: there is hardly anything to be found in the way of basic description of the gross and microscopic characteristics of the primary growth, but there are several detailed descriptions of the anatomical pathways of invasion. The TNM system of staging of laryngeal carcinoma (Spiessl et al. 1982) divides laryngeal tumours into supraglottic, glottic and subglottic. This classification is the result of: a) attempts to extrapolate a theory of embryological development of the larynx into the sphere of tumour pathology, and b) the confusion of the extent of the epithelial origin with the invasion of the cancer. A quotation from Bocca et al. (1968) is a typical example of the assumptions underlying pathological studies and classifications of the past 30 years:

The supraglottic or vestibular portion of the larynx which includes the epiglottis and the ventricular bands develops from the buccopharyngeal anlage whereas the glottic and subglottic portions develop from the tracheobronchial anlage. This is enough to understand why the larynx virtually consists of two hemilarynges each of them with its own different derivation and with its largely independent laryngeal circulation. This means that each of these hemilarynges may become invaded by cancer independent of one another, and that the extension of cancer is limited within the boundaries of embryological demarcation. As a consequence, supraglottic cancer shows no tendency to become glottic cancer, and glottic cancer never shows a tendency to invade the supraglottic stage. Exceptions to this rule may rarely be observed. As a matter of fact cancer invading both areas at one time is most often regarded as transglottic or primary plurifocal.