Ameloblastoma in a female Wistar rat.

A spontaneous ameloblastoma of the right mandible is described in a 120-week-old female Wistar rat (strain Chbb: THOM). The tumour had a locally aggressive growth pattern and was histologically characterized by sheets and islands of odontogenic epithelium bounded by a palisaded layer of ameloblast-like cells. Because of multifocal keratinizing squamous metaplasia of the stellate reticulum tissue, the tumour was classified as an acanthomatous ameloblastoma. Cyst formation, areas of stromal hyalinization and enamel matrix-like inclusions were further characteristics of the neoplasm. The epithelial elements stained strongly positive for broad spectrum cytokeratins.

Aberrant craniopharyngeal structures within the neurohypophysis of rats.

Aberrant craniopharyngeal structures within the neurohypophysis were analyzed in 17 rats, originating from four different colonies of Sprague-Dawley- and Wistar-derived strains, which were used for toxicity studies in five different laboratories. Males were more frequently affected than females. The incidence of these findings, which occurred spontaneously and mainly in aged rats, was very low. Predominant features included tubular or acinar glandular structures, rarely embedded in a fibrous stroma, and, as a rule, not compressing adjacent tissue. In some cases, large cysts filled with colloid-like, amorphous material and cellular debris were present. The tubular structures consisted of a rather flat epithelium, while the cystic elements were lined by a cuboidal or columnar, rarely ciliated epithelium, containing goblet cells, or by a stratified squamous epithelium. These structures reacted positively for cytokeratin. Acinar structures mimicked salivary glands of the serous or mucinous type. In a few cases, small, round or fusiform cells were present. Distribution and predominance of the various epithelial structures depended on the strain and colony of rats. Considering the ontogenic development of the pituitary gland, the morphological aspect of these lesions, their immunoreactivity and former reports on similar findings, we concluded that these rats have aberrant craniopharyngeal structures within the pars nervosa of the hypophysis, originating from remnants of the oro-pharyngeal epithelium of the craniopharyngeal duct (RATHKE's pouch). These lesions, which occurred in different strains and colonies of laboratory rats, represent heterotopias or choristomas, consisting of non-neoplastic growth disturbances. Being of a distinctly non-proliferative nature, they should not be confused with craniopharyngiomas.

Elective Neck Dissection in patients with stage T1-T2N0 carcinoma of the anterior tongue.

OBJECTIVES: The presence of neck metastases represents one of the most important prognostic factors for carcinomas of the anterior tongue, the five-year survival rate being under 20% in patients with regional metastases. The aim of this study was to demonstrate the efficacy of prophylactic selective neck dissection in patients without detectable nodal metastases. MATERIALS AND METHODS: A matched case-control study with prospective follow up was conducted in ENT Department of Coltea Clinical Hospital for 86 patients with T1-T2N0 stage carcinoma of the anterior tongue surgically treated between January 2000 and January 2005 with or without concurrent selective supraomohyoid neck dissection (SND). The patients were divided in two groups, comparable in age and sex distribution. Descriptive statistics, risk of recurrences, Kaplan Maier five-year survival curves and the global and specific mortality rates were performed using EpiInfo software. The level of significance was established at p<0.05. RESULTS: After a mean follow-up time of 90.5 months, for all variables considered as outcomes of SND efficacy evaluation, significance differences (p < 0.05) were registered between groups: the frequency of patients who developed neck metastases was lower in the group of subjects who underwent prophylactic selective neck dissection; the all-cause mortality rate at the end of the follow-up period was three times lower in SND study group compared with controls; the specific mortality rate due to regional recurrences was five times lower in test-group compared with controls. CONCLUSIONS: Our study suggest that prophylactic selective neck dissection could be indicated for patients with T1-T2N0 carcinomas of the anterior tongue in order to increase both overall and free of recurrence survival time, respectivelly.

The epidemiology of hypopharynx and cervical esophagus cancer.

At the beginning of the 21st century the hypopharynx and the cervical esophagus cancer represents a major issue for all countries of the world. The epidemiology of the hypopharynx and cervical esophagus cancer deals with the spread of the disease in the human population with regard to sex, age, profession, time and space, as well as risk factors that contribute to these phenomena. The main goal is to investigate the causes and the factors involved in the development of the tumors at the pharyngoesophageal junction, knowledge that contributes to the latest therapeutic assessment through interdisciplinary collaboration (E.N.T. surgeon, general surgeon, radiation oncologist, chemotherapist, and nutritionist). The epidemiology of the hypopharynx and cervical esophagus cancer includes three major areas of interest: descriptive (the study of the spread in mass population), analytical (the study of causal risk factors on the disease) and experimental (that verifies by experiments on animals the prior identified hypothesis).