Introduction:
Submucosal lesions appear as growths beneath the mucosa that lines the gastrointestinal tract. These lesions or nodules do not produce symptoms and are found while performing diagnostic or screening tests. They are usually benign lesions but may turn malignant in some cases. Endoscopic ultrasound is the best method to find the location and extent of the lesion. These lesions are removed by endoscopic resection, endoscopic mucosal excavation, and submucosal tunneling endoscopic resection.
What Causes Submucosal Lesions?
Submucosal lesions arise from the mesenchymal cells (loosely arranged and undifferentiated connective tissue cells). However, the causes are still unclear.
What Are the Types of Submucosal Lesions?
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Gastrointestinal Stromal Intestinal Tumors: Gastrointestinal stromal intestinal tumors generally occur between 50 and 60 years of age. They usually appear in the stomach and the small intestine. They are mostly benign (non-cancerous). However, in some cases, they can be malignant (cancerous and tend to spread).
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Symptoms: They are generally asymptomatic, but a few symptoms occur depending on the tumor size.
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Pain in the belly region.
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Intestinal bleeding due to rupture of mucosal ulcerations.
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Obstructions in the bowel.
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Anorexia (unable to eat).
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Treatment: They are removed by performing complete surgical resection. It is done if the lesion turns malignant or if they cause symptoms.
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Leiomyoma: Leiomyoma occurs in the esophagus’s distal part. They are benign. Moreover, appear as small, asymptomatic lesions.
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Symptoms: Occasionally, they cause dysphagia (swallowing difficulty).
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Treatment: Asymptomatic lesions do not require treatment. However, symptomatic nodules undergo surgical removal.
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Lipoma: Lipomas are benign fat tumors and can arise in any part of the gastrointestinal tract.
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Symptoms: They are usually asymptomatic but can cause a few signs when the lesions enlarge.
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Intestinal obstruction.
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Intestinal bleeding.
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Abdominal pain.
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Treatment: Surgical resection is considered when the lesion is large or symptomatic. Otherwise, lipomas do not require treatment.
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Granular Cell Tumors: Granular cell tumors are neoplasms that occur in rare conditions. Neoplasms are abnormal tissue mass that appears when cells multiply and grow abnormally, exceeding their normal growth and division capacity. They can be both benign and malignant. They are generally seen in the oropharynx and the esophagus.
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Treatment: Surgical resection is recommended for significant, symptomatic, and malignant lesions. While monitoring is sufficient in small, asymptomatic, and benign tumors.
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Duplication Cysts: Duplication cysts occur due to congenital abnormalities (birth defects) in the gastrointestinal tract. These cysts are rare, asymptomatic, and are usually found while performing screening or diagnostic procedures.
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Symptoms: They are asymptomatic but occasionally cause symptoms like,
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Treatment: Fine-needle aspiration (FNA) and surgical excision are the treatment choice. Fine-needle aspiration is a biopsy type where a thin needle is inserted into the lesion, and the contents are aspirated and removed.
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Carcinoid Tumors: Carcinoid tumors can be benign or malignant. Carcinoid tumors in the gastrointestinal arise in the ileum, rectum, and appendix.
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Symptoms:
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Pain in the abdomen.
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Diarrhea.
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Constipation.
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Treatment: Surgical resection coordinated with regular monitoring of the lesions are the treatment choice.
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Ectopic Pancreas: Ectopic pancreas lesions consist of pancreatic tissues. They occur in the distal part of the stomach, duodenum (first part of the small intestine), and jejunum (middle part of the small intestine). They also have a tendency to turn malignant.
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Symptoms: They mostly do not cause symptoms. However, a few symptoms mentioned below are noted in a few patients.
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Pancreatitis (enlargement of the pancreas).
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Intestinal bleeding.
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Intestinal obstruction.
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Treatment: The treatment depends on the severity of the lesion. Depending on the severity, it can vary from observing the lesion to surgical resection.
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What Tests Are Performed to Diagnose Submucosal Lesions?
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Standard Endoscopy: In endoscopy, a thin, flimsy tube with a lens, light, and portal for instruments is inserted into the mouth to reach the internal part of the gastrointestinal tract. It helps view the inner part for abnormalities.
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Capsule Endoscopy: In capsule endoscopy, a capsule with a camera is made to swallow. The capsule captures images of the digestive tract, and any abnormalities noted are further investigated and treated. The captured images are recorded in a tracker attached to the patient's wrist or belt. The tracker will be handed over to the doctor when the capsule is removed from the body after a bowel movement.
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Endoscopic Ultrasonography: In endoscopic ultrasonography, the flexible endoscope has a light, lens, and portal for instruments, and an ultrasound device is attached to it. This ultrasound device emits sound waves to obtain images of the inside of the gastrointestinal tract.
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Catheter Probe Endoscopic Ultrasonography: In catheter probe endoscopic ultrasonography, a mini probe or a catheter is attached to the end of the flexible endoscope tube. When inserted into the gastrointestinal tract, this device provides high-resolution images of the targeted structure.
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Endoscopic Ultrasound-Guided Fine Needle Aspiration Biopsy: In endoscopic ultrasound-guided fine needle aspiration biopsy, a thin needle and an ultrasound probe are added to the endoscope tube. The sound waves are emitted from the probe, and with this as a guide, the needle is advanced to the targeted structure, and the samples are aspirated for pathological study.
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Barium Contrast in X-Ray: A white chalky substance called barium is made to swallow, and X-ray radiations are projected on the target structure. This barium coats the intestinal tract, highlighting the structures in the X-ray image.
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Computerized Tomography (CT) Scan: Computerized tomography uses X-ray radiation to capture images of internal organs at different angles on a computer. It gives detailed pictures of the targeted organs, tissues, and bony structures.
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Magnetic Resonance Imaging (MRI): Magnetic resonance imaging uses high-frequency sound waves and radio waves to capture images of internal organs and soft tissue structures.
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Positive Emission Tomography (PET) Scan: Positive emission tomography uses radioactive tracers like hydrogen, sulfur, phosphorus, iodine, etc. This test helps determine the biochemical functions of the organs and tissues. Positive emission tomography reveals normal and abnormal metabolic activities in the body.
How Are Submucosal Lesions Treated?
Submucosal lesions do not require treatment if they are asymptomatic or if the lesions are small in size. However, if the lesions cause symptoms, enlarge, or have a tendency for malignant transformation, the below-mentioned procedures are performed.
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Surgical Resection: Surgical resection is the removal of the lesion along with a layer of normal tissue. This also removes any remnants present in the tissue.
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Endoscopic Mucosal Resection: In endoscopic mucosal resection, a specialized probe is attached to the endoscope, and suction is used. The lesions are injected with a solution for them to rise, and this also reduces bleeding. Suction is further used to pull up the lesion, and a thin wire loop is placed over the lesion. Electric current is passed through the wire, which helps cut the lesion. Also, this procedure promotes wound healing.
The sliced lesion is removed from the intestinal tract through a wire basket and is sent for laboratory testing for further analysis.
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Submucosal Tunneling Endoscopic Resection: The gastric wall has four linings, namely the mucosa, submucosa, muscularis propria, and serosa. The lesions usually arise from the submucosal region. In this procedure, a special fluid is injected into the skin proximal to the lesion.
This creates submucosal fluid cushioning between the submucosa and the muscularis propria. The lesion is then scooped with a specialized instrument attached to the endoscope creating a tunnel from the lateral part of the lesion. This leaves the mucosal layer intact. Finally, the opening of the tunnel is sealed with an endoscopic clip.
What Are the Complications of Submucosal Lesions?
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Perforation: Perforations or holes on the site of the endoscopic procedure are pretty common. They need further management.
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Bleeding: Minor bleeding on the site of the endoscopic procedure is expected and will resolve in a few days.
Conclusion:
Submucosal lesions in the gastrointestinal tract are usually benign but can sometimes turn malignant. Also, most submucosal lesions are asymptomatic and appear small in size, and they are often left untreated and monitored regularly. Treatment is recommended when these lesions have a tendency to turn malignant, lesions enlarge and cause symptoms like abdominal pain, obstruction, and bleeding. They are surgically removed, and also endoscopic resection and endoscopic mucosal resections are done. However, most of the lesions are asymptomatic and are found during routine screening tests or other diagnostic procedures. They are then subjected to further investigation procedures like fine-needle aspiration biopsy, endoscopic ultrasound, capsule endoscopy, etc. Although most of the lesions are benign, a regular check-up and visiting the doctor when mild symptoms appear will reduce complications.
