What Is a Pulmonary Blastoma? Childhood Lung Cancer

4 types of pulmonary blastoma

• Type Ir pulmonary blastoma
  • In type Ir, the “r” stands for regressed or regressing. It is similar to type I pulmonary blastoma in microscopic cell appearance but cancerous cells have regressed (the tumor has grown smaller).
  • This type has a better prognosis compared to the other types of pulmonary blastoma.
  • The cure rate for this type of blastoma is approximately 89%, but there are higher chances of recurrence as type II or III pulmonary blastoma.
• Type I pulmonary blastoma
  • This type is mostly found in young children (from birth to 2 years of age) with one or more cysts in the lungs (air-filled pockets).
• Type II pulmonary blastoma
  • This type includes both cystic growths and solid parts. Sometimes, the tumor can spread to the brain and other sites in the body.
• Type III pulmonary blastoma
  • These are solid tumors and spread to the brain or other parts of the body.

What causes pulmonary blastoma?

Pulmonary blastoma (PB) is the most common childhood lung cancer, but it has no connection to adult lung cancers which are often related to tobacco use or asbestos exposure. Although type Ir PB may be found at any age, other types are mostly found in children under ages 7-8, rarely in older children, and even more rarely in adults. 

Researchers speculate that PB may be an indication of an underlying variation in a gene called DICER1, inherited from a parent. In approximately 40% of children with PB, there are other childhood cancers or abnormalities in the child or their immediate or extended family.

Genetically, pulmonary blastomas occasionally show association with:

• TP53 mutation
• p53 and MDM2 protein accumulation

What are the symptoms of pulmonary blastoma?

Depending on the child’s age and the type of pulmonary blastoma, two different sets of symptoms include:

• Compression of the normal lung tissue caused by air pockets can lead to:
  • Respiratory distress
  • Mild to severe dyspnea (breathing difficulty)
  • Pneumothorax (air leaks in the space between the lung and chest wall)
  • Lung infections, such as pneumonia
• Generalized symptoms such as:

How is pulmonary blastoma diagnosed?

Pulmonary blastoma (PB) may not be initially suspected when a child exhibits symptoms because PB is rare and other conditions of the lung are more common. Tests that may be recommended include the following:

• Medical history and physical examination: To check for signs of disease such as lumps or anything that seems to be unusual.
• Chest X-ray: May show an air-filled pocket (cyst) or a solid mass or typical findings of pneumonia (lung infection).
• Chest computed tomography (CT) scan: Series of detailed pictures of the chest and abdomen are taken from different angles.
• Positron emission tomography (PET) scan: Pictures are taken after injecting a small amount of radioactive glucose into a vein so that malignant tumor cells show up brighter due to their higher uptake of glucose than normal healthy cells.
• Bronchoscopy: Uses a bronchoscope (a thin, tube-like instrument with a light and lens) to view the inside of the trachea and large airways in the lungs for abnormalities.
• Biopsy: To diagnose and remove the cyst or solid tumor.

How is pulmonary blastoma treated?

Treatment of pulmonary blastoma (PB) is determined based on the type:

• Type I: Treatment of choice is typically surgery and sometimes chemotherapy.
• Types II and III PB: Surgery is often the first choice of treatment, but due to the size and location of the tumor, only a biopsy can be performed. Treatment may also include chemotherapy and radiation therapy.

When standard treatments do not work high-dose chemotherapy followed by autologous stem cell transplantation may be recommended.

How serious is pulmonary blastoma?

Both type II and III PB are serious and aggressive malignancies. About 50%-70% of children with these types are cured.

Like many cancers, types II and III PB can metastasize (spread through the blood to other areas of the body), most often to the brain or other areas such as the bones, liver, and diaphragm, and in rare cases to other organs.

Prognosis depends on the type of pulmonary blastoma, whether it has spread at the time of diagnosis, and whether it is completely removed via surgery.