Spectrum of glandular differentiation in experimental carcinoma of the esophagus induced by 2,6-dimethylnitrosomorpholine under the influence of esophagojejunostomy

How phenotype guides management of non-conventional squamous cell carcinomas of the larynx?

Although the majority of laryngeal malignancies are the conventional squamous cell carcinomas (SCC), a wide variety of malignant epithelial tumors can affect the larynx. Current treatment guidelines are designed to guide clinicians in management of conventional laryngeal SCC. Less is known about the biological behavior and responsiveness to therapy and overall outcomes of other malignant epithelial lesions. Because a spectrum of disease biology is represented by these rare phenotypes, an understanding of the basic biology can help direct management to optimize clinical outcome in this group of patients. This review provides a critical analysis of literature relating to the diagnosis, management, and outcome of patients with non-conventional squamous malignant epithelial neoplasms of the larynx. Particular attention is paid to features which are at variance with the conventional SCC and how these impact on management of these rare tumors.

Adenosquamous carcinoma of the head and neck: criteria for diagnosis in a study of 12 cases

AIMS

Adenosquamous carcinoma (ASC) of the head and neck is an unusual neoplasm in which a general consensus with regard to diagnostic criteria has not yet been reached. In this study we report the clinicopathological results of 12 ASCs, with special attention to their histological and immunohistochemical characteristics in order to define this neoplasm more precisely.

METHODS AND RESULTS

All the patients were male with a peak incidence in the sixth decade of life. The tumours were located most frequently in the larynx and oral cavity, followed by the nasal cavity and pharynx. ASCs had two distinct histological components. The most extensive one was an usual keratinizing squamous cell carcinoma, arising from the surface epithelium, where characteristically severe dysplasia or carcinoma in situ was found in all cases. The second component was an adenocarcinoma, usually displayed in the deepest areas of the tumour. Evidence of origin from salivary or seromucinous glands was not found. Immunohistochemical studies demonstrated in most cases positivity of glandular differentiated areas for carcinoembryonic antigen (CEA) (11/12), CK7 (9/12) and CAM5.2 (7/12), whereas the squamous cell component was unreactive or reacted only focally for these markers. High-molecular-weight cytokeratin 34BE12 was positive in both components and CK20 was always negative. All cases showed high expression of Ki67 antigen. Most of them had overexpression of p53 (8/12) and DNA aneuploidy (10/12). Fifty percent of patients with ASC died of disease after a mean period of 23 months (range 12-35 months).

CONCLUSIONS

ASC of the head and neck is an aggressive neoplasm that originates in the surface epithelium of the upper respiratory tract. Severe dysplasia or carcinoma in situ is usually found and its recognition helps to make the diagnosis. In addition to mucin stains, positive immunoreactivity for CEA, CK7 and CAM5.2 helps to identify the glandular component.

Changing role of in vivo models in columnar-lined lower esophagus

Columnar-lined lower esophagus (CLE) or Barrett's esophagus (BE) is caused by chronic reflux of the gastrointestinal tract and can progress to invasive adenocarcinoma. However, the pathophysiology, cell of origin, and management of this condition is incompletely understood. This review evaluates the role of in vivo models in resolving these debates. A search was performed on the Ovid and Pub Medline for 1964-2001 and Cochrane Collaboration. The keywords used were adenocarcinoma, animal model, Barrett's esophagus, columnar-lined esophagus, esophageal neoplasms, and esophageal carcinogenesis. All relevant papers were scrutinized and an attempt at tabulation was made. In vivo models have been used at several stages of debate on the pathophysiology of BE. They provide conclusive evidence for its acquired nature secondary to duodenogastroesophageal reflux. The cell of origin of experimental BE may arise from adjacent columnar epithelium, basal layer multipotent cells, or esophageal glands. Experimental work on BE is lacking in assessing therapeutic modalities.

Expression of cyclin D1 and p53 and its correlation with proliferative activity in the spectrum of esophageal carcinomas induced after duodenal content reflux and 2,6-dimethylnitrosomorpholine administration in rats

Alterations in expression of the p53 and cyclin D1 genes have been implicated in the development of esophageal carcinomas in both humans and animal models. We hypothesize that altered expression of cyclin D1 and p53 may be involved in the sequential development of esophageal carcinomas with glandular differentiation induced by the carcinogen, 2,6-dimethylnitrosomorpholine (DMNM) in rats with duodenal content reflux esophagitis. In the present study Sprague-Dawley rats were given DMNM 15 days after performing an esophago-jejunostomy in order to induce chronic duodenal content reflux esophagitis. Expression and localization of p53, cyclin D1 and Ki-67 were examined by immunohistochemical analyses. Twenty of 24 animals developed different types of esophageal carcinomas, including pure squamous carcinoma, adenosquamous carcinoma and pure adenocarcinoma. Undifferentiated basaloid areas were frequently observed in these tumors. Cyclin D1 overexpression was observed in hyperplastic lesions and increased through dysplasia and in undifferentiated areas of infiltrating carcinoma. Cyclin D1 expression coincided with increased Ki-67 expression and decreased along with cell differentiation. The p53 immunohistochemical pattern was parallel to that of cyclin D1, although the percentage of positive cells was usually smaller in all lesions and increased p53 expression started at the dysplastic stage. These findings suggest that overexpression of cyclin D1 may be an early event in DMNM-induced rat esophageal tumorigenesis, causing increased proliferation of esophageal stem cells. Abnormal p53 expression may then be required to promote the development of neoplastic transformation from dysplastic epithelium through invasive phenotype, being more evident in cancer cells with squamous differentiation.

Duodenal-content reflux esophagitis induces the development of glandular metaplasia and adenosquamous carcinoma in rats

Recent studies have demonstrated that refluxed duodenal contents cause esophageal carcinoma in rats without exposure to carcinogens. The histopathological spectrum of these carcinomas includes squamous-cell carcinoma, adenocarcinoma and adenosquamous carcinoma. Pure adenocarcinomas are thought to arise in areas of columnar metaplasia adjacent to the anastomosis, similar to Barrett's esophagus in humans. In contrast, the histogenesis of adenosquamous carcinomas is unclear. The purpose here was to investigate the pathogenesis of esophageal adenosquamous carcinomas in a time-course experiment of chronic duodenal-content reflux without carcinogen. Forty-two 8-week-old male Sprague-Dawley rats were divided into seven groups and exposed to duodenal-content esophageal reflux during 10, 15, 20, 25, 30, 35 and 40 weeks, respectively. All animals underwent an esophagojejunostomy with gastric preservation in order to produce chronic esophagitis. The rats received a standard diet without addition of carcinogens. An increasing incidence of glandular metaplasia and carcinoma was observed over the time course, starting at 20 weeks. After 40 weeks of reflux, multiple foci of glandular metaplasia and adenosquamous carcinoma were found in 83 and 50% of the animals, respectively. Most of the carcinomas occurred in the middle and proximal esophagus and had a dual pattern of differentiation, glandular and squamous. These findings confirm that duodenal content reflux alone has a carcinogenic effect. We propose that chronic duodenal reflux induces the development of metaplastic cells with glandular differentiation from the stem cells of squamous epithelium, and that glandular metaplastic foci are the morphological element from which tumors with a dual pattern of differentiation arise.