What is the thymus gland and its tumors
The thymus is located behind the sternum, between the lungs, above the heart. During childhood, it plays a key role in the maturation of T lymphocytes, and by adulthood it decreases and is replaced by fat. Thymic tumors are divided into thymomas, which are composed of epithelial cells and usually grow slowly, and the more aggressive thymic carcinomas. Thymomas are classified according to histological types, but the main practical significance is whether the tumor remains inside the capsule or grows beyond it: the amount of treatment and prognosis depend on this.
- The thymus is located in the anterior mediastinum behind the sternum
- With age, iron is replaced by adipose tissue
- Thymomas grow slowly and are often limited to the capsule
- Thymus carcinoma is more aggressive
- Capsule germination determines tactics and prognosis
Link to myasthenia gravis and other autoimmune diseases
Myasthenia gravis is a disease in which antibodies disrupt signal transmission from nerve to muscle. Its main symptom is pathological fatigue: there is strength, but it quickly dries up with repeated movements and is restored after rest, so in the evening the condition is worse than in the morning. The eyelid and oculomotor muscles are usually the first to suffer, hence drooping eyelids and double vision. A significant proportion of patients with thymoma have myasthenia gravis, and vice versa, therefore, for newly diagnosed myasthenia, a chest CT scan is required. Less commonly, thymoma is accompanied by other autoimmune conditions.
- Myasthenia gravis is a disorder of signal transmission to the muscle.
- Weakness increases in the evening and after exercise
- Drooping eyelids and double vision are a common onset
- For myasthenia gravis, a chest CT scan is required.
- Other autoimmune conditions are possible
- Removal of the thymus often improves the course of myasthenia gravis
Symptoms
In about a third of patients, thymoma is found by chance on a chest X-ray taken for another reason, and there are no complaints. For some people, the first manifestations of myasthenia gravis appear. The third group of symptoms is associated with the mechanical pressure of the growing tumor on the mediastinal organs: pain or heaviness behind the sternum, persistent cough, shortness of breath, hoarseness when the recurrent nerve is involved. When the superior vena cava is compressed, a characteristic picture develops: swelling of the face and neck, swelling of the veins in the chest, a feeling of fullness in the head when bending over.
- Asymptomatic and incidental discovery
- Muscle weakness, drooping eyelids, double vision
- Pain and heaviness behind the sternum
- Cough and shortness of breath
- Hoarseness of voice
- Swelling of the face and neck due to compression of the superior vena cava
- Difficulty swallowing
Diagnostics
A mass in the mediastinum is often first noticed on a plain chest x-ray, but the main method is CT with intravenous contrast: it shows the size, borders, relationship to the vessels and signs of invasion. MRI helps distinguish thymoma from cysts and residual thymic tissue. In case of muscle weakness, antibodies to acetylcholine receptors are determined and electroneuromyography is performed. A biopsy is not always performed: if the tumor is operable and the picture is typical, it is removed entirely so as not to disturb the capsule, and the diagnosis is established based on the removed specimen.
- Chest X-ray as a first step
- CT chest with contrast
- MRI to clarify the nature of the formation
- Antibodies to acetylcholine receptors
- Electroneuromyography for muscle weakness
- Biopsy for inoperable and questionable formations
Treatment and observation
The main method is surgical removal of the thymus gland along with the tumor and surrounding fatty tissue. The operation is performed through an incision in the sternum or minimally invasively, endoscopically, depending on the size and extent. Complete removal of the tumor that does not extend beyond the capsule is often sufficient. In case of germination, incomplete removal or aggressive histological type, radiation therapy is prescribed, and in case of widespread forms, chemotherapy is prescribed. Patients with myasthenia gravis are prepared for surgery together with a neurologist. Observation after treatment is long, since relapses are possible years later.
- Removal of the thymus with tumor and fiber
- Open or endoscopic approach
- Radiation therapy for germination and incomplete removal
- Chemotherapy for common forms
- Preparation of patients with myasthenia gravis together with a neurologist
- Long-term follow-up with follow-up CT
- Monitoring neurological symptoms after surgery
