Mediastinal tumors - Thymoma
What is it?
Thymic tumors account for less than 1% of all cancers and are therefore considered rare cancers with an incidence of about 0.15 cases per 100,000 people. The incidence is higher over age 65 with no significant differences between men and women.
The thymus is an organ located in the space enclosed anteriorly by the sternum, posteriorly by the heart and large vessels, and laterally by the two lungs. It plays an important role within the lymphatic system in the development of certain lymphocytes.
Thymic neoplasms are divided into:
- thymoma: a tumor that arises from the epithelial cells lining the thymus. It arises in adulthood, over the age of 40. Thymoma may be associated with other immune-related diseases such as myasthenia gravis. Typically this tumor is localized to the thymus with a fairly indolent evolution; over time however it can become more invasive involving the pleura and lungs. Rarely, pleural and lymph node metastases can also be found;
- thymic carcinoma: accounts for about 5-10% of thymic tumors. It originates from the cells of the thymus lining epithelium, but has significantly greater invasiveness characteristics. It grows rapidly and frequently tends to spread to other locations;
- thymic carcinoid: almost never presents with symptoms associated with other diseases such as myasthenia gravis. Thymic carcinoid is a particularly rare tumor of neuroendocrine origin. It affects men more frequently and, compared with thymoma, has a greater tendency to spread to other sites or recur. Thymic carcinoids may be associated with multiple endocrine neoplasia syndrome type 1 (MEN-1), which is a rare genetic disease.
Which are the symptoms?
About 30-40% of patients with thymoma are asymptomatic. The most frequently observed symptoms may be:
- chest pain;
- persistent cough;
- breathlessness or dyspnea.
Very often the symptoms may instead be related to myasthenia gravis, a condition often associated with the presence of a thymoma. Myasthenia gravis is an autoimmune disease characterized by the presence of antibodies directed against the neuromuscular plaque and especially at the acetylcholine receptor. The presence of antibodies directed against the neuromuscular plaque inhibits the effect of acetylcholine resulting in muscle weakness. In these cases, the symptoms may be:
- difficulty keeping the eyes open (eyelid ptosis);
- fatigue (asthenia);
- double vision or diplopia,
- difficulty swallowing;
- respiratory failure.
How is it diagnosed?
Les tests diagnostiques pour les néoplasmes thymiques comprennent :
- Radiographie thoracique : Ce test initial aide à identifier les anomalies dans la région thoracique.
- CT (tomodensitométrie) : C'est le test le plus couramment utilisé. Il permet de déterminer l'étendue et les caractéristiques de la masse thymique, qui apparaît généralement comme une masse ovoïde ou ronde dans le thymus.
- IRM (imagerie par résonance magnétique) : Ce test fournit des images détaillées de la masse thymique et aide à évaluer si la tumeur a envahi les organes voisins.
- TEP (tomographie par émission de positons) : Ce test évalue l'activité métabolique de la tumeur, fournissant des informations sur son niveau d'activité.
- Biopsie du thymus : Elle peut être réalisée par thoracoscopie ou, plus fréquemment, sous guidage CT. Elle est réservée aux tumeurs plus grandes nécessitant un traitement oncologique préopératoire.
- Dosage des anticorps (anti-récepteur de l’acétylcholine ou anti-récepteur muscarinique) : Ce test permet de vérifier la présence de myasthénie grave, souvent associée au thymome.
Suggested exams
How is it treated?
Treatments of thymic neoplasms include:
- surgery: represents the gold standard of treatment for thymic neoplasms and is often the only treatment required for patients diagnosed at an early stage (stage I and II). Very often surgery is possible through minimally invasive access (videothoracoscopy, or robotic surgery). Its use allows for rapid postoperative recovery, improved quality of life, and a low rate of surgery-related complications;
- radiation therapy: sometimes used after surgery (adjuvant therapy) to prevent disease recurrence, especially in cases where the disease is extracapsular;
- chemotherapy: chemotherapy treatment involves the use of cisplatin as the drug of first choice combined with etoposide.
Suggested procedures
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