Primary carcinomas are rarely encountered in the laryngeal ventricle of Morgagni. They are classified into the subgroup of supraglottic laryngeal carcinoma in the TNM classification system of malignant tumors. However, detailed investigations have not hitherto been made on the possible occurrence of carcinomas in this region of the larynx. To find out whether the laryngeal ventricle could be the site of carcinogenesis, the author examined squamous metaplasia in the mucosal epithelium of 60 human laryngeal ventricles which were taken from 38 larynges removed operatively from patients with laryngeal carcinoma (14 cases), hypopharyngeal carcinoma (20 cases), carcinoma of the upper esophagus (two cases), tracheal carcinoma (one case) or thyroid carcinoma (one case). The patients consisted of 31 males and 7 females, with an age distribution of 44 to 80, average 62.7. The laryngeal ventricles were selected for investigation only when they did not show any carcinomatous invasion macroscopically. Macroscopic observations were performed after gross staining with pyronin Y, which permits differentiation of squamous metaplasia from respiratory epithelia. Tissues were embedded in paraffin, sectioned serially and stained with hematoxylin and eosin. The clinical records of the patients were also made.
The results are summarized as follows:
1. Squamous metaplasia of the stratified ciliated epithelium was found in 38 out of 60 specimens (63%) of the laryngeal ventricles examined.
2. The metaplasia seemed to be precipitated by smoking or exposure to radiation, along with aging.
3. The incidence and extent of metaplasia of the ventricular mucosa depended on the disease entity which had necessitated total laryngectomy, and the metaplasia was most prominent in cases with the supraglottic type of laryngeal carcinoma.
4. The metaplastic epithelium was occasionally associated with hyperplasia or dysplasia of the epithelium.
5. Microinvasive carcinoma was found in one laryngeal ventricle with severe metaplasia. These findings suggested a possible de novo carcinogenic process in the laryngeal ventricle through squamous metaplasia of the respiratory epithelium. From this observation, the author proposes to call carcinoma of this region of the larynx the ventricular type of laryngeal carcinoma.
