Pleuropulmonary blastoma (PPB) is a type of cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs that primarily affects children. It often develops in the tissues of the lung and the pleuraa thin layer of tissue covering the lungs and the wall of the interior chest cavity, but can develop in the organs located in the mediastinumthe space between the lungs that holds many important structures, including the heart, trachea and oesophagus such as the heart, tracheathe tube that connects your voicebox (larynx) to the lungs, also known as a windpipe and oesophagus.
The respiratory system is composed of the nose, mouth, trachea (windpipe) and airways (bronchi and bronchioles) that lead to the lungs, which is where the breathing process primarily occurs. Each lung is made up of lobes, with the right lung being composed of three lobes and the left only having two lobes to accommodate room for the heart. The lungs sit on top of a muscle called the diaphragm, which separates the abdomenstomach, stomach area, belly from the chest. The diaphragm works by contracting/flattening when we inhale, pulling air into the lungs. When we exhale, the diaphragm relaxes and pushes air out of the lungs. The space between the lungs is called the mediastinum, and holds several important structures, including the heart, trachea, oesophagus and lymph nodessmall bean-shaped structures that filters harmful substances from lymph fluid.
Each lung is covered by a thin layer of tissues called pleurae, that protects and cushions the lungs. There are two types of pleurae: the parietal and visceral. The parietal pleura is the thicker tissuea group of cells that work together to perform a function that lines the inner surfaces of the thoracic cavity, while the visceral pleura lines the surface of the lungs.
PPB is a paediatric cancer that affects the genders equally, and tends to develop in children under the age of eight (most commonly between the ages of three and four). However, anyone can develop this disease.
Types of Pleuropulmonary Blastoma
There are three primary types of PPB, that are categorised by the characteristics of the tumoura tissue mass that forms from groups of unhealthy cells itself.
Type I Pleuropulmonary Blastoma
Type I PPB is characterised by the development of cystsabnormal growths that are usually filled with liquid or air in the lungs, with no evidence of solid tumour parts. These tumours may have some cancerous cellsthe basic structural and functional unit of all living things present, and generally occur in patients under three years old. Type I PPB usually has a good prognosisto predict how a disease/condition may progress and what the outcome might be.
Type Ir Pleuropulmonary Blastoma
Type Ir PPB is a subtype of type I PPB that shares the same characteristics, without the presence of cancerous cells. The ‘r’ after type I stands for regressed, which means the cysts have gotten smaller.
Type II Pleuropulmonary Blastoma
Type II PPB shows evidence of cysts and solid tumour parts with cancerous cells. This type of PPB often develops in children around three years old, and can metastasise (spread) to the brain and/or other parts of the body. Type II PPB may be aggressive, and may not have as good of a prognosis as type I PPB.
Type III Pleuropulmonary Blastoma
Type III PPB is a completely solid cancerous tumour that often develops around four years of age. It is often aggressive, likely to metastasise, and may not have as good of a prognosis as other PPB subtypes.
Some of the information regarding types of PPB was obtained from the Childhood Pleuropulmonary Blastoma Treatment (PDQ) page published by the National Cancer Institute.
Treatment
If PPB is detected, it will be staged and graded based on size, metastasiswhen the cancer has spread to other parts of the body, also known as mets, and how the cancer cells look under the microscope. Stagingthe process of determining how big the cancer is, where it started and if it has spread to other areas and grading helps your doctors determine the best treatment for you.
Due to the rarity of this disease, the staging system for this tumour solely relies on determining the type of PPB you have. The factors taken into consideration when staging your tumour may include:
- Presence of cysts.
- Presence of solid tumour.
- Presence of cancerous cells.
- Rate of metastasis (if any).
Your doctor may also recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. This is often performed after a biopsyremoval of a section of tissue to analyse for cancer cells and can help guide treatment options for you.
Treatment is dependent on several factors, including age, stage of disease and overall health.
Treatment options for PPB may include:
- Surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence, potentially including:
- Lobectomya surgical procedure where a lobe of an organ (e.g. the lung) is removed.
- Extrapleural pneumonectomyremoval of the diseased lung, part of the pericardium (membrane covering the heart), part of the diaphragm and part of the parietal pleura.
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells (only in patients with PPB types II and III).
- Watch and waitthe close monitoring of a cancer without giving treatment until symptoms appear or worsen (only in patients with type Ir PPB).
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Risk factors
Due to the rarity of PPB, there have been very few riskthe possibility that something bad will happen factors identified. The factors found to potentially increase your risk of developing this disease include:
- Having a mutation of the DICER1 gene.
- Having a family history of cancer.
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Symptoms
PPB may be asymptomatic in the early stages of the disease. As the tumour develops, some symptoms may occur, including:
- Persistent cough.
- Difficulty breathing.
- Unexplainable shortness of breath.
- Fevers.
- Persistent lung infections, such as pneumonia.
- Unexplainable weight loss and/or loss of appetite.
- Chest pain.
Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have PPB, they may order the following tests to confirm the diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Imagingtests that create detailed images of areas inside the body tests, potentially including:
- Chest x-raya type of medical imaging that uses x-ray beams to create detailed images of the body .
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
- Blood teststesting done to measure the levels of certain substances in the blood.
- Exploratory surgeryan exploratory surgical procedure used for conditions that cannot be confirmed by scans and tests alone, potentially including:
- Bronchoscopyan examination of the trachea and lungs with a small, flexible instrument known as a bronchoscope.
- Mediastinoscopyexamination of the mediastinum (area between the lungs) with a small, flexible instrument called a mediastinoscope .
- Thoracoscopyexamination of the inside of the chest cavity with a small, flexible instrument known as a thorascope.
- Biopsy.