Esophageal leiomyomas are the most common benign tumors of the esophagus.
Leiomyomas are the most common, benign mesenchymal tumors of the esophagus. Mesenchymal tumors account for two-thirds of all benign lesions of the esophagus. These tumors originate in the smooth muscle cells. The etiology and pathogenesis are unclear.
There is a higher incidence of leiomyoma of the esophagus in men when compared to women; this is in the order of 2:1. The most frequent occurrence is usually between the ages of 20 to 50 years. The most typical location of these tumors is in the lower two-third of the esophagus. The occurrence of these tumors in the upper one-third of the esophagus accounts for only 10% of all leiomyomas of the esophagus. Majority of the tumors are detected when they are less than 5 cm in size. Rarely, they grow to be larger than 10 cm and then, they are called giant leiomyoma of the esophagus. These may occur as single or multiple tumors.
Leiomyoma of the esophagus is known to be a slow-growing tumor with low malignant potential. Occasionally these leiomyomas grow larger and present as tumors greater than 10 cm in diameter, and then they are called giant leiomyomas of the esophagus. Giant leiomyomas of the esophagus may present as a mediastinal mass. The most frequent site of occurrence of this tumor is the lower two-thirds of the esophagus, and this distribution reflects the relative amount of smooth muscle cells present along the wall of the esophagus. When the leiomyomas situated in the distal esophagus reach a large size, they can press on the cardia of the stomach.
On histopathological examination, the esophageal leiomyomas appear as circumscribed lesions composed of intersecting fascicles of bland spindle cells with abundant cytoplasm. These well-differentiated smooth muscle cells which are of the spindle type are arranged as braids. These bundles are demarcated by adjacent tissue or a definite connective tissue capsule. The spindle cells intersect with each other at varying angles. The tumor cells have blunt elongated nuclei and display minimal atypia and very few mitotic figures. Hence, this tumor is thought to have a low malignant potential. These cells, when evaluated with immunohistochemistry, is found to stain positive for Desmin, alpha-smooth muscle actin while staining negative for the CD34, CD117, and S100 protein.
Leiomyomas of the esophagus rarely cause symptoms when they are smaller than 5 cm in diameter. When these tumors grow larger, they become more symptomatic in patients. The most common symptoms are dysphagia, chest pain, vague retrosternal discomfort, heartburn, and occasionally regurgitation. Rarely they can cause gastrointestinal bleeding when the tumor erodes through the mucosa. Apart from the nonspecific and ill localized symptoms associated with esophageal leiomyomas, no physical findings are present. There appears to be no consistent pattern of symptoms according to the anatomical location of the tumor. In the rare case of a giant leiomyoma of the esophagus, patients report persistent cough. Large esophageal leiomyomas usually grow outward, so dysphagia need not be present and does not reflect the size of such tumor. Many of these tumors are discovered incidentally during endoscopic procedures or radiological tests. With the increasing use of endoscopy and radiological investigation, the number of cases diagnosed is increasing.
Often, a diagnosis of esophageal leiomyoma is made as an incidental finding during routine investigation or screening for upper gastrointestinal (GI) pathology. The most common radiological study used to investigate any suspected esophageal lesions is an upper GI barium contrast study or oesophagogram is as it is the least invasive, simple, and most commonly available investigation. In a Barium contrast series of the upper GI tract an, an esophageal leiomyoma will be seen as a filling defect projecting into the lumen of the esophagus in the images. The typical appearance is a smooth concave space occupying lesion underlying a normal mucosa. It is easy to recognize a sharp angle at the junction of the tumor and healthy tissue. When an endoscopy is performed, these tumors can be identified as relatively mobile submucosal swellings. An upper GI endoscopy will confirm the presence of a submucosal tumor by clearly visualizing a mass protruding into the lumen of the esophagus, with normal looking mucosa covering the swelling. A CT scan is a valuable investigation in confirming the diagnosis. CT scan will show a mass of uniform density arising in the esophageal wall. Currently, endoscopic ultrasonography (EUS) has become a critical investigation for diagnosis of esophageal leiomyoma. An endoscopic ultrasound will delineate the intramural nature of the tumor with no associated mediastinal lymph node enlargement. Endoscopic ultrasonography can display the five-layered structure of the esophageal wall with the tumor shown as a mass of uniform density, low-intensity acoustic shadowing, and a clear boundary.
All though there seems to be no consensus on the treatment protocol according to the size of the tumor. Thus all patients with symptomatic tumors are advised excision or enucleation of the tumor. The conventional surgical approach has been by an open thoracotomy. After this, an enucleation of the tumor with an esophageal myotomy or a resection of the tumor with the esophagus is performed. Esophageal resection may be indicated in giant leiomyoma of the esophagus or tumors involving long segments of the esophagus. Tumors of the middle third can be approached using a right thoracic route and tumors of the distal one-third can be accessed through a left-sided approach. The main morbidity associated with open thoracotomy approach are wound pain and atelectasis. Minimally invasive approaches or video-assisted thoracoscopic surgery (VATS) have progressively gained acceptance in the last few years. Video-assisted thoracoscopic surgery is the preferred approach for enucleation of upper two-thirds leiomyoma. For extra-mucosal excision or enucleation the outer esophageal muscle is incised longitudinally, and then careful dissection is performed to separate and remove the leiomyoma from the underlying mucosa. Thoracoscopic minimally invasive approach has resulted in a shorter postoperative stay, reduced pulmonary complications and decreased wound pain when compared with the open procedure. Recently Endoscopic submucosal dissection and enucleation of esophageal leiomyomas are increasingly being performed. Some centers have used the Da Vinci robot-assisted thoracoscopy to perform the surgery. Although the standard surgical practice is to approximate the muscle layer following a myotomy and enucleation, there are reports to substantiate that large myotomies or extra-mucosal defects can be left open without the development of a subsequent complication. Oesophageal resection as a treatment is reserved for those with very large tumors. Asymptomatic tumors which are less than 1 cm are managed by regular follow-up and expectant treatment.
Large leiomyomas need to be differentiated from gastrointestinal stromal tumor (GIST), by histopathology and by using immunohistochemistry. However, the presenting symptom can mimic oesophageal cancer leading to a diagnostic dilemma.