The esophagus is a fibromuscular tube and forms part of the upper gastrointestinal tract. It extends from the lower border of the pharynx to the cardias, or the upper portion of the stomach. The wall of esophagus has four tissue layers. They are from inside out: mucosa, submucosa, muscular layer, and fibrous layer.
Anatomically, the esophagus has three parts. The uppermost is called cervical followed by the thoracic and the lowermost part, called abdominal part. Tumors of the esophagus may arise from one of the four layers in any of the three anatomical divisions.
There are benign as well as malignant tumors of the esophagus. Benign tumors of the esophagus include leiomyomas that arise from the muscular layer, and they grow in the walls of the esophagus. Mucosal polyps arise from the mucosa, fibroma from the submucosa and fibrous layer, and there are also hemangiomas and lipomas.
Malignant tumors of the esophagus are adenocarcinoma, squamous cell carcinoma, and other rare carcinomas. Leiomyomas are the most common variety of benign esophageal tumors, and account for 66% of cases. Among all types of malignant tumors, adenocarcinoma accounts for only 3% of cases while squamous cell carcinoma constitutes 93% of cases.
Primary lymphomas of the esophagus are very rare, as well as secondary metastasis of a lymphoma to the esophagus. Sometimes, the malignancies of the lower portion of the esophagus are only extensions of a primary gastric carcinoma. Esophageal malignancy is the sixth most common malignancy in the world. It is mostly seen in Iran, China, and parts of Africa.
Adenocarcinoma is seen in patients with Barrett’s esophagus, Plummer Vinson syndrome, gastroesophageal reflux disease, radiation exposure, and obesity. The most important etiological factor of esophageal cancers is the consumption of alcohol, chewing tobacco, and smoking habit. Risk factors for developing squamous cell carcinoma include achalasia, caustic esophageal injury, and consumption of hot beverages. Adenocarcinoma is also associated with TP53 mutations during the early stages of the neoplasia, or infections caused by human papilloma virus and Helicobacter pylori.
Another risk factor worth mentioning is the development of esophageal adenocarcinoma from Gastroesophageal reflux disease. This complication occurs as a result of dysplasia in the mucosa of the esophagus. Dysplasia is a consequence of the acid from the stomach, which causes erosion of the normally squamous epithelium, which is later converted into columnar epithelium.
The most important clinical features of esophageal tumors include:
Initially there is no pain, and patients may only feel discomfort while having solid meals. Pain symptoms reflect the extension of the tumor beyond the walls of esophagus. As the tumor increases in size, it expands and puts pressure upon the walls and nerves within the wall, causing chest pain. In other cases, pain may also be located in the retrosternal area or the epigastrium.
In cases of benign tumors such as mucosal polyps, lipomas, fibromas and esophageal hemangiomas, they typically cause pain due to ulceration on the surface of the tumors as they grow towards the wall of the esophagus and become pedunculated. Pain is usually referred in the back instead of the chest. There may be odynophagia (pain upon swallowing) due to the narrowed lumen of the esophagus.