Pleuropulmonary Blastomas (PPBs) in Children

Pulmonary blastomas are classified into three subtypes:

1. Type I
   • PPBs of this type is purely cystic cancers that manifest as multiloculated, air-filled cysts with thin septa. 
   • The cysts are lined with benign respiratory epithelium and mesenchyme, and some mesenchymal cells show skeletal differentiation.
   • Nearly 33 percent of PPBs detected at the age of eight months are detected in this stage. 
   • Type I PPBs are often unilateral, unifocal, peripheral, larger than 5 cm in size, and occur more among men (57 percent of cases).
   • Type Ir
     • Although the transition from type I to type III happens, many type I lesions do not develop into type II and type III tumors.
     • Type I PPBs can evolve to type Ir where r implies regression.
     • It accounts for 23 percent of the overall type I population.
     • The appearance of type Ir PPBs resembles that of type I, but it does not have scattered primitive malignant cells.
     • The median age of diagnosis for type Ir PPB is 46.5 months, compared to eight months for type I PPBs.
     • It has been noted that all individuals who died after being diagnosed with type I PPBs, had advanced to type II or type III PPBs, whereas no deaths were documented in those who developed type Ir.
2. Type II
   • PPBs of this type are referred to as cystic and solid.
   • The solid component arises from the proliferation of the malignant mesenchymal cells.
   • Type II PPBs account for almost 33 percent of all cases, with an equal male-to-female ratio.
   • Type II appears later than type I at an average age of 35 months (95 percent diagnosed by 6.8 years of age). 
   • Type II PPBs are rarely seen before the age of 12 months.
3. Type III
   • These PPBs develop at a later age, with an average age of diagnosis of 41 months.
   • Usually, these do not get noticed before the age of 12 months.
   • Type III PPB is made up of tumor cells, with no cystic gaps in between.
   • The solid portions of PPBs of types II and III are histologically similar, with a mixed, sarcomatous appearance.
   • Interspersed foci of anaplasia and characteristics of embryonal rhabdomyosarcoma, chondrosarcoma, or necrosis may be present in these sarcomatous cells.
   • In certain type III PPBs, necrosis progression may be sufficient to create pseudocysts, but this does not de-escalate the tumor to type II status.
   • Given the histologic resemblance between types II and III, care must be taken during biopsy to collect sufficient specimens to capture the cystic component present in type II PPB.

Solid tumors of type II and III may spread to the brain.

The symptoms of pulmonary blastomas in children include:

• Excessive cough that does not go away
• Chest discomfort
• Difficulty breathing
• Wheezing
• Pulmonary infections
• Fever
• Abdominal discomfort
• Loss of appetite
• Unwanted weight loss
• Fatigue

The doctor will collect a detailed history of your health habits, diseases, and treatments. Physical examination is done to identify any abnormalities or symptoms consistent with tumors.

Radiological imaging techniques such as chest X-ray, CT scan, MRI, positron emission tomography scan, and bone scan are done to identify possible tumors and abnormalities of the soft tissue.

Other tests include:

• Bronchoscopy
  • An examination technique where a bronchoscope is introduced into the trachea and lungs through the nose or mouth.
  • A bronchoscope is a narrow tube with a light and a camera.
  • It detects possible abnormalities of the trachea and major airways in the lung.
  • It may also extract tissue samples, which are then examined under a microscope for malignant cell changes. This procedure is known as a biopsy.
• Thoracoscopy
  • A surgical procedure that examines the organs inside the chest for abnormalities.
  • A thoracoscope is a thin, flexible tube with a light and a camera, which is inserted into the chest through an incision made between two ribs.
  • It can collect suspected or abnormal tissue or lymph nodes that need to be examined under a microscope for cancerous changes. This procedure is sometimes used to remove a section of the esophagus or a lung.
  • In a thoracotomy, the chest is opened for a better view after a larger, more extensive incision is made between the ribs.
  • This surgery may be performed if the thoracoscope cannot reach certain tissues, organs, or lymph nodes.

The standard treatments for pleuropulmonary blastomas (PPBs) in children include surgery and chemotherapy. The use of targeted therapy for PPBs is under clinical trials.

• Surgery
  • Is performed to remove cysts and solid tumors.
  • Sometimes, a lobe or one side of the lung is completely removed.
• Chemotherapy
  • Chemotherapy with cisplatin is found to be well tolerated by children.
  • Usually, the chemotherapy drug is administered intravenously following surgery to kill the remnant cancer cells.
  • Sometimes chemotherapy may be given before surgery to shrink large masses, which may be difficult to remove surgically in their actual size.
• Clinical trials
  • Once malignancy is identified, people with PPBs may be asked to take part in a clinical trial for both their benefit and to aid the doctor in better understanding the course of cancer.
• Targeted therapy
  • A cancer treatment in which medications or other substances are used to kill cancer cells. 
  • Targeted treatments have fewer side effects than chemotherapy or radiation therapy.
  • Targeted therapy is being investigated for the treatment of recurrent PPBs.