Histological types of laryngotracheal tumors induced in Syrian golden hamsters by nitrosomorpholine and nitrosopiperidine.

The chronic oral administration of nitrosomorpholine (NM) and nitrosopiperidine (NP) to 360 adult Syrian golden hamsters of both sexes resulted in the induction of a high incidence of laryngo-tracheal tumors, which in the group treated with 0.01% solution of NM affected up to 80% of the males. A total of 232 different laryngo-tracheal tumors were found. 36 of these were located within the supraglottic and glottic larynx, 62 were within the subglottic and glottic larynx, and 134 arose within the trachea. Among the laryngeal supraglottic and glottic tumors there were 18 squamous cell carcinomas, 16 squamous cell papillomas and only 2 mixed cell mucoepidermoid papillomas. All the subglottic laryngeal tumors and tracheal tumors were mixed cell mucoepidermoid papillomas. In this study, the squamous cell carcinomas observed within the larynx of hamsters bear morphological and biological similarities to their tumor counterpart found in the larynx of adult man. The laryngeal squamous papillomas observed in this experiment are not similar to the squamous papillomas occurring in man during infancy and childhood. The mixed cell mucoepidermoid papillomas of the hamster trachea and subglottis are a peculiar neoplasm of this species, which morphologically and biologically differs from the cases of tracheal papillomatosis described in man, as well as from the mucoepidermoid tumors of major and minor salivary gland origin also seen in this latter species.