Pleuropulmonary Blastoma

What is pleuropulmonary blastoma?

Pleuropulmonary blastoma or PPB is a rare lung tumor, most common in children under the age of 7 years. There are 4 types of PPB. Type I PPB is an air filled cyst which contains a layer of malignant (cancerous) cells. These cells can grow quickly and sometimes Type I PPB can progress to Type II or Type III. Type II PPB has both cystic and solid components and Type III PPB is a solid and often very large tumor within the chest. Type I PPB does not always progress and in some cases the quickly-growing cells may go away (or “regress”) leading to a thin walled cyst, which is called Type Ir or Type I PPB with regression.

How is it diagnosed?

Type I PPB is most commonly diagnosed in children under the age of 1 year. Type II PPB is diagnosed at an average age of 3 years. Type III PPB is diagnosed at an average age of 3.5 years, usually under age 7 years. Type Ir PPB may be diagnosed at any age and may be found incidentally when a CT scan is done for another reason. Individuals with PPB may have difficulty breathing, collapsed lung (pneumothorax), fevers or difficulty gaining weight or may be initially thought to have pneumonia.

How is is treated?

Type I PPB is treated with surgery. Chemotherapy may be needed for some individuals with Type I PPB, depending on specific circumstances. Types II and III PPB require surgery with chemotherapy and often radiation therapy. Type I PPB is usually only found in the lung. Types II and III PPB may spread to other areas of the body and imaging studies of multiple areas of the body are usually done to determine if the PPB has spread. For all children with PPB, medical exams and imaging are done on a scheduled basis after the PPB is removed. The exact timing of of these exams is determined by the type of PPB and other circumstances.

Where does it come from?

Many children with PPB have a change in a gene called DICER1 that makes the gene not work properly. When this gene is not working properly, tumors are more likely to occur. Other benign (not cancer) or malignant tumors that may be seen in individuals with DICER1 mutations include a benign kidney tumor called cystic nephroma, another kidney tumor called Wilms tumor, thyroid nodules or goiter or thyroid cancer, ovarian tumors, and, very rarely, certain childhood brain tumors including pituitary blastoma and pineoblastoma. While some individuals with DICER1 changes develop one or more tumors or have findings such as lung cysts of thyroid nodules, many are healthy throughout their lifetime.

When a child or adult is diagnosed with one of the conditions above, genetic testing can determine if a DICER1 change is present. If a DICER1 change is found, DICER1 testing may be recommended for family members. Screening for other DICER1-related conditions is recommended for those who do have the change in their DICER1 gene so that if a tumor arises, it can be found early, when it’s most treatable.

What else do I need to know?

The International Pleuropulmonary Blastoma Registry was established at Children’s Minnesota in 1988 to study PPB and other related conditions. The Registry has enrolled children from 43 U.S. states and 49 countries and serves as a resource for health care providers, patients and families. For more information visit www.PPBregistry.org or email [email protected].

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