Thymoma in Children

Reviewed on 12/6/2022
Thymoma in Children
Thymomas in children, especially patients younger than 10 years old, are highly aggressive.

Thymomas are very uncommon neoplasms in children, accounting for less than one percent of mediastinal tumors in the pediatric population.

  • Thymomas can develop in the cells that cover the exterior surface of the thymus. 
  • Thymomas resemble healthy thymus cells under a microscope.
  • Thymomas can range from slow-growing tumors that rarely migrate outside the thymus to more aggressive tumors that might potentially spread to neighboring organs in the chest, such as the pleura.

The thymus gland is a small organ located in the upper chest under the breastbone. It is an integral part of the lymph system and produces special white blood cells known as T-lymphocytes (T-cells), which aid in the fight against infection. The thymus is most active during infancy, grows to its largest size during puberty, and then gradually diminishes with age. Thymomas often occur between the lungs, and at the front of the chest and are frequently discovered during a routine chest X-ray.

Pediatric thymomas are more aggressive than adult thymomas. Especially, in pediatric patients younger than 10 years, thymomas are considered highly aggressive.

They are usually discovered by accident, but they can be symptomatic. Thymoma in children can manifest in various ways, many of which are nonspecific and overlap with cardiopulmonary pathologies.

It is very difficult to diagnose and treat pediatric patients due to the rarity of their cases. There aren't many reports on how to treat pediatric thymoma tumors. In patients with thymoma, a combination of surgery, chemotherapy, and radiotherapy may provide satisfactory results. The stage of the thymoma tumor is an independent predictor of survival. Children with thymomas that have been completely resected at the time of diagnosis have an excellent prognosis. Management and prognosis are based on early diagnosis and complete resection.

More large-scale, multinational, or institutional analyses with long-term follow-up are needed to provide more information for optimal management strategies and outcomes.

What Are the Common Sign and Symptoms of Thymoma in Children?

Children with thymoma may or may not experience symptoms. If the patient is symptomatic, the signs and symptoms may be vague and overlap with those of other cardiorespiratory conditions.

Possible signs and symptoms of thymoma in the pediatric population may include:

  • Persistent cough
  • Shortness of breath
  • Difficulty breathing
  • Progressive respiratory distress
  • Decreased breath sounds
  • Severe pallor
  • Intermittent fever
  • Anorexia or weight loss
  • Sweating
  • Chest pain
  • Tightness in the chest
  • Upper back pain, which may radiate to the left flank 
  • Tachypnea (28 breaths per minute)
  • Suprasternal and intercostal retractions
  • Trouble swallowing
  • Hoarseness
  • Double vision
  • Swelling in the face or arm
  • Drooping eyelids 
  • Fatigue
  • Dizziness

Patients with thymoma may also have symptoms suggestive of superior vena cava syndrome (SCVS). SCVS is a combination of symptoms that occur when the superior vena cava is blocked or compressed. It is frequently connected with cancer although it can also be caused by an infection, a blood clot, or an implanted medical device. Severe instances, especially in children, can be fatal.

Symptoms of SCVS may include:

  • Face/neck swelling
  • Distended neck veins
  • Dyspnea
  • Orthopnea
  • Upper extremity swelling
  • Distended chest veins
  • Conjunctival suffusion or redness of the conjunctiva

Although the symptoms might be caused by a variety of conditions, a physical examination by the doctor is recommended to rule out any other health conditions.

What Are the Potential Causes of and Risk Factors for Thymoma in Children?

Thymomas have no known causes or risk factors. Researchers are still investigating what triggers this condition in children.

Possible risk factors for thymoma in children

  • Preexisting respiratory conditions: Studies report that children who are diagnosed with thymoma incidentally, may have preexisting respiratory conditions, such as asthma and/or pneumonia.
  • Ethnicity: Thymomas are more common in African Americans. Asians and Pacific Islander heritage may have an increased risk of thymoma.
  • Autoimmune conditions: Thymoma is linked to autoimmune diseases as well, including good syndrome and pure red cell aplasia. People who develop thymoma usually have one of the following immune system or hormone disorders:

According to the American Cancer Society, 30 to 65 percent of patients with thymomas also have MG, whereas not all people with MG have thymomas.

What is the Masaoka–koga Staging System for Thymoma?

The Masaoka-Koga staging system is the most popular staging system to evaluate patients with thymoma.

Four stages of thymoma as per the Masaoka-Koga staging system

  1. Stage I: Thymomas in this stage are completely encapsulated macroscopically, and no microscopic capsular invasion is seen. The tumor develops within the capsule that surrounds the thymus gland. Cancer has not spread to other organs.
  2. Stage II: Thymoma has expanded from the thymus gland into the surrounding fat or the lining of the chest cavity.
    • Stage IIA: Microscopically transcapsular invasion.
    • Stage IIB: Macroscopic invasion into surrounding fatty tissue, or grossly adherent to but not breaking through mediastinal pleura or pericardium.
  3. Stage III: Macroscopic invasion into neighboring organs (such as pericardium, great vessel, or lungs). Thymoma has spread to the lung, the sac around the heart, or the large blood arteries that supply the heart with oxygen and nutrients.
  4. Stage IV:
    • Stage IVA: Pleural or pericardial metastases (thymoma has spread to the lungs or the heart).
    • Stage IVB: Lymphogenous or hematogenous metastasis (thymoma has spread to the circulatory or lymphatic systems).

The Masaoka-Koga staging method is used to guide treatment decisions in both adults and children.

What Are the Treatment Options for Children Diagnosed With Thymoma?

Doctors may propose the best course of therapy based on the stage of the tumor, its classification, and whether it has spread to other regions of the body. Surgery is the most often-used option for thymoma treatment. Typically, a median sternotomy is performed to breach the breastbone and remove the thymoma and surrounding tissue. Laparoscopic surgery may be used to treat smaller thymomas.

Six treatment options for children with thymoma

  1. Surgery
    • The primary treatment option for thymoma.
    • Surgery is done to remove the tumor and other diseased cells or organs. Nevertheless, carcinoma may return following treatment.
  2. Radiation therapy
    • A cancer treatment that employs high-energy X-rays or other forms of radiation to either kill or prevent cancer cells from developing.
    • External radiation therapy is the use of a machine located outside the body to direct radiation toward the cancerous location.
  3. Chemotherapy
    • Uses medications to halt the proliferation of cancer cells, either by killing them or preventing them from growing. 
    • Chemotherapy medications enter the circulation and can reach cancer cells throughout the body whether administered orally or injected into a vein or muscle (systemic chemotherapy).
  4. Hormone therapy
    • Eliminates or inhibits the function of hormones, preventing cancer cells from proliferating. 
    • Hormones are chemicals produced by glands in the body and circulated through the circulation. Certain hormones can promote the growth of certain malignancies. 
    • If tests reveal that the cancer cells contain receptors for hormones, medications may be used to limit hormone synthesis or prevent them from acting.
    • Thymoma can be treated with hormone treatment, such as corticosteroids or octreotide.
  5. Targeted therapy
    • Uses medicines or other substances to locate and destroy specific cancer cells. 
    • This therapy is less likely to kill normal cells than chemotherapy or radiation therapy.
    • Other types of targeted therapies are being researched for the treatment of recurrent thymoma 
    • Targeted therapy is being studied for the treatment of thymoma and thymic carcinoma that has recurred (come back).
  6. Clinical trials
    • Participating in a research study may be the best therapy option for some individuals. 
    • Clinical trials are a component of cancer research. Many of today's mainstream cancer therapies are based on prior clinical studies. 
    • Patients who participate in a clinical study may receive care and can be among the first to receive a novel therapy.
    • Patients can enroll in clinical trials before, during, or after beginning cancer therapy after discussing it with their doctors. 
    • Some clinical trials only enroll participants who have not previously received therapy. Other studies look at therapy for patients whose cancer has not improved. There are also clinical studies that look for novel strategies to prevent cancer from recurring or to lessen the adverse effects of cancer treatment.

It's crucial to note that all thymoma therapies have the potential to cause unpleasant side effects. Doctors can offer answers to any concerns regarding what to anticipate following the treatment and how to minimize pain and adverse effects.

What is the Outcome of Children With Thymoma?

Patients with thymic cancer have a worse five-year survival rate than patients with thymoma. In a small study of thymic cancer patients, overall survival rates stood at 38 percent after five years and 28 percent after 10 years.

Treatment without surgery and the presence of metastatic disease were linked to less favorable results. Early diagnosis and appropriate treatment may increase recovery chances for children diagnosed with thymoma.

Reviewed on 12/6/2022
Image Source: Getty image

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