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CONGENITAL PULMONARY AIRWAY MALFORMATION (CPAM)

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CONGENITAL PULMONARY AIRWAY MALFORMATION (CPAM)

 

Congenital pulmonary airway malformation is a rare defect characterized by a cystic mass of abnormal lung tissue in a baby during pregnancy.

  • This mass varies in size and may change in appearance during the pregnancy. They can be solid or filled with fluid.
  • In most cases, this abnormal tissue is located in one lung, and cannot function as a normal lung tissue.
  • In less than 2% of all cases, it can occur in both lungs.
  • The abnormal tissue is usually present in one lobe (section) of the affected lung.
  • The left lung comprises 2 lobes and the right lung has 3 lobes. Congenital pulmonary airway malformation may affect any of these lobes.
  • This condition occurs in approximately 1 in 30,000 pregnancies.
  • The condition can become life-threatening if the cystic mass grows so large as to affect the growth of surrounding organs.
  • The large mass may cause pressure against the heart leading heart failure.
  • Congenital pulmonary airway malformation (CPAM) can be separated into five types (0-4), depending on the features.
  • CPAM type 1 is the most common with large cyst and has a favorable outcome.
  • CPAM type 2 consists of medium sized cysts and often has a poor prognosis. This is because it is associated with other congenital anomalies including those of the cardiac and skeletal system, genitourinary.
  • Other types are rare.

CAUSES

The cause of the condition is unknown. The condition occurs sporadically, and it is not associated with or related to any maternal factor including age, race, or environmental exposure.

 

SYMPTOMS

  • Increased breathing difficulty
  • Pneumothorax, an abnormal collection of air in the pleural space and the chest wall

DIAGNOSIS AND TREATMENT

The condition is often diagnosed during a routine prenatal ultrasound. Congenital pulmonary airway malformation will appear as a bright mass in the area of the chest where only the lung is supposed to be seen.

To confirm the diagnosis,

A fetal MRI will be carried out to better understand the size and location of the mass.

A fetal echocardiogram will also be carried out to assess heart function and rule out any structural heart defect.

To predict the risk of the condition, a CPAM volume ratio, or CVR will be used. This is measured by using the formula length x width x anteroposterior diameter / 2), divided by the head circumference.

For every fetus with a CPAM, the CVR measurement will be carried out every week.

By comparing the CVR measurements, the rate of growth of the CPAM can be determined, as well as whether it will become life-threatening.

 

TREATMENT

Treatment options may include:

Prenatal treatment option

  • Steroid treatment for a mass that is solid and growing rapidly.
  • Open fetal surgery to remove the mass. This is carried out in extreme cases where the fetus heart is in danger.
  • A special needle to drain a fluid-filled cyst. The needle is inserted through the womb into the mass and the fluid drained
  • Early delivery starting at 32 weeks of pregnancy

Other treatment options

If the cystic mass is so large that it may pose a danger during birth, a special surgical type of delivery known as EXIT surgery may be carried out. During this delivery, the baby remains attached to the placenta by its umbilical cord while the lung function is evaluated. If breathing is normal, the baby can be completely delivered and the mass removed later. If otherwise, the mass is removed immediately while the mother’s placenta supports the baby. Once the procedure is complete, the umbilical cord is cut and the baby is fully delivered.