Thymoma is characterized as a growth or tumor of the thymus gland mainly located in the epithelial cells of the specified organ. It can be either benign or malignant in nature.
Thymomas are generally described by professionals according to their extent of spread from the thymus gland to other parts of the body. In most cases, these appear as normal tumors but in some cases they show a high degree of spread making it very difficult to treat.
The population in their 3rd and 4th are considered more vulnerable for thymomas as they are most likely to develop in these decades of life. However both genders; male and female are equally vulnerable to this disease.
The exact underlying cause of this disease is not known yet. As well as there are no described risk factors that can act as a base for the development of thymomas.
The prognosis for the later stages of this disease including stage III or IV is considered worse in comparison to stage I and II thymomas. Approximately 7% of the cases can metastasize to other body organs involving, bones, pleura, liver, or brain.
It has been stated in a study that more than 40% of the experimental patients of stage III and IV tumors lasted for approximately 10 years after the diagnosis of the disease. Moreover, these patients were in their late 50s at the time of diagnosis.
Many deaths have been reported among the patients who administered the yellow fever vaccine after undergoing the thymectomy for thymomas. This could have happened because of the poor response of the T-cells towards attenuated vaccines of yellow fever.
CT scan: Initially upon presentation of some associated clinical manifestations, professionals suggest an immediate CT scan to critically examine the situation of the disease. This scan generally confirms the presence of the tumor and its estimated size in the specified area. The enhanced vascular enlargement may pose the risk of malignancies.
Biopsy: After confirmation of the presence of the tumor, a needle biopsy is performed that is generally CT-guided and the samples from the lesions are extracted to proceed further examination. A very few biopsies may pose the risk of pneumomediastinum, mediastinitis, or damage to the heart involving associated large blood vessels.
Histological examination: The extracted samples are then sent to the pathologist for further clarifications. The staging and classification are done according to the results obtained from this examination.
Laboratory tests: There is some lab test that is suggested to evaluate any other associated medical conditions. These tests may include;
- Protein electrophoresis
- Antibodies to the acetylcholine receptor (indicative of myasthenia)
- Electrolytes check
- Liver enzymes test
- Renal function test
Usually the thymomas do not present any clinical manifestations (asymptomatic) leading to the easy diagnosis of the disease which accounts for 50% of the patient population. It has been stated that approximately one-third of the patient population is diagnosed with thymomas due to the associated immunosuppressive disorders such as myasthenia gravis (MG). So the patients who are asymptomatic in this disease, diagnosis for other diseases may lead to thymomas.
But other cases may present the clinical signs and symptoms which are highly dependent upon the size of the tumor and associated pressure insertion on the neighboring organs in this specified area. The most common symptoms may involve;
- Severe chest pain induction
- shortness of breath or difficulty in breathing
- persistent cough among the patients
- superior vena cava syndrome
- dysphagia (difficulty in swallowing food)
Some less common symptoms may appear in some cases which involve;
- elevated body temperature (Fever)
- frequent night sweats
- Sudden weight loss
In some cases the disease may have a high spread rate and quickly extends to the heart or the lining of the lungs or occasionally to the tissues lying outside the chest cavity. But the spread outside the chest cavity is highly unlikely to occur and only account for less than 7% of cases.
The most staging system that has been widely used by the medical experts is mainly based on the anatomical degree of the disease at the time of the performance of surgical procedure and called as Masaoka Staging System (MSS).
This staging system involves the following four stages of the disease and some of these involves the sub-classifications;
I: Completely encapsulated. (It is the first stage that presents the complete encapsulation of the area.)
The second stage is further divided into phases and the first phase involves the microscopic invasion into the adjacent fatty tissues through the capsule.
IIA: Microscopic incursion through the capsule into surrounding fatty tissue
IIB: Macroscopic incursion into a capsule. (the second phase involves the macroscopic invasion)
III: Macroscopic incursion into neighboring organs
The fourth stage is further divided into phases involving the following.
IVA: Pleural or pericardial implants
IVB: Lymphogenous or hematogenous metastasis to aloof (extra-thoracic) areas.