Introduction
The thymus is an organ located behind the sternum, and obtains its maximum weight at puberty and then it faces involution. Thymus helps in the development of cell-mediated immunity during the early stages of life. Thymoma is a tumor or neoplasm that develops with the cells of epithelium constituting the thymus.
It is known to be the most common tumor involving the front portion of the mediastinum and the prevalence ranges from 20 % - 25 % of all the tumors of the mediastinum and 50 % of masses involving the anterior location of the mediastinum. It shows a peak in incidence during the fourth and fifth decades of life and there is no sex predilection.
How Is It Caused?
The exact etiology has not been proven yet but it can be associated with certain syndromes like myasthenia gravis, dermatomyositis, systemic lupus erythematosus, Cushing syndrome, etc.
What Are the Signs and Symptoms of Thymoma?
Usually, the cases can be asymptomatic and it can be diagnosed during a routine examination or some other imaging studies being done to diagnose another case. However, at times it can show some symptoms that can depend on the size of the tumor. In that case, the following symptoms can be noticed:
1. Pain in the chest.
2. Difficulty in breathing or shortness of breath.
3. Cough.
Sometimes, the following symptoms may also occur but are less common in frequency:
1. Fever.
2. Loss of weight.
3. Sweating at night.
There have been cases wherein the tumor spreads to adjacent tissues like the heart, lungs, etc., and may cause symptoms associated with that particular region. Although children are known to have less prevalence than adults in developing thymoma, the symptoms are higher in children. The trachea or near trachea is the most common location for this tumor in children and thus, causing respiratory symptoms.
How Can It Be Diagnosed?
Initially, when you visit your physician, you will be asked certain questions about your past medical history and the symptoms you face at present. Following that, certain physical examinations will be done and then, testing for suspected syndromes may be done, if required and finally, imaging studies can be done. Some imaging studies that can be preferred are CT (computed tomography), radiography, positron emission tomography (PET), etc. Also, FNAC (fine needle aspiration cytology) can be done later to confirm the diagnosis.
What Are the Stages in Thymoma?
Thymoma can be staged using the Masaoka system. This is a very commonly used system for this tumor and includes stage I, II, III, and IV. Stage II and IV can be further divided into stages II a, II b, IV a, and IV b.
The Masaoka Staging System which is based on the anatomical extent of the lesion or tumor at the time of surgery is as follows:
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I: Completely encapsulated.
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IIA: Microscopic invasion through the capsule into surrounding fatty tissue.
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IIB: Macroscopic invasion into the capsule.
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III: Macroscopic invasion into adjacent organs.
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IVA: Pleural or pericardial implants.
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IVB: Lymphogenous or hematogenous metastasis to distant (extrathoracic) sites.
How Can It Be Treated?
The management can be either medical or surgical.
Medical Management
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Chemotherapy
It is based on literature. Literature suggests that thymoma is sensitive to drugs, especially stage IV thymoma tumors.
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Radiotherapy
This may also help in shrinking the tumor and it is beneficial to use as an adjunct or with the surgical method.
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Corticosteroids
This is based on case reports. Case reports have shown that orally delivered corticosteroids have helped in the regression of tumors that are invasive in nature.
Multidisciplinary Approach
This type of approach can be used for tumors that cannot be resected. Based on certain studies or case reports, induction chemotherapy, surgical resection, postoperative radiation therapy, and consolidation chemotherapy can be preferred.
Options in the Future
Studies have proven biological and molecular changes in thymoma. Thus, a deeper understanding and evidence of such characteristics of tumors like specific tumor markers, etc., will help in establishing a better treatment plan.
Surgical Management
In most of the cases, the first line of treatment option for such tumors lies around surgical excision. This involves specific patient preparation, resection type, and also, the prognosis.
Are There Any Complications?
Yes, there have been reports of certain complications especially after the radiation therapy and sometimes, after surgical management. Some of the complications include radiation pericarditis, radiation pneumonitis, pulmonary fibrosis. The deaths have been reported in these tumors after or during treatment, and hence, the physician needs to assess and decide the proper treatment plan associated with radiation, chemotherapy, or surgery.
What Is the Prognosis?
The prognosis depends on various factors like the age of the patient, size of the tumor, the involvement of adjacent tissues, etc. The prognosis is known to be worse for symptomatic patients as they might have a malignant type of lymphoma. The most important factor to be considered before deciding the prognosis rate is the invasion of surrounding tissues by the tumor. Histologically, the features should be observed. The overall inspection of the tumor physically should also be done.
In other patients, there is a better prognosis after treatment and the survival rates have been documented to be around 10 years. The patients who have had thymectomy for the management of thymoma must be informed about the major side effects that can happen after the vaccination for yellow fever. The reason for the same has been attributed to the inadequate response of the T-cells to the live attenuated vaccine of yellow fever. In worst-case scenarios, even deaths have been reported.
Conclusion
Thymoma is a tumor involving the thymus gland and it can be benign or malignant. It has both better as well as poor prognosis depending on various factors. Early diagnosis can help in better management of the disease. Online medical platforms are proving to be a gift by helping patients to communicate with their physicians or specialists anywhere anytime. Consult your physician or specialist to get more details about this tumor.
