Pulmonary alveolar proteinosis (PAP) is a very rare disease in which the air sacs of the lungs (alveoli) do not work properly.

The alveoli become filled with an oily, protein-type material called ‘surfactant’. This is either because too much is produced or because it is not cleared properly. As a result, the lungs cannot get oxygen into the bloodstream as easily as normal leading to symptoms such as breathlessness, coughing and chest pain.

What are the typical symptoms of PAP?

Most people diagnosed with PAP have some of the following symptoms although the combination varies between patients:

  • Breathlessness (the medical term is dyspnoea) either on exertion/activity but sometimes even at rest
  • Decreased or decreasing ability to exercise
  • Coughing, sometimes with production of white or yellowish phlegm (sputum)
  • Chest pain  in various types and degrees of severity
  • Fever or sweats
  • Generalised aches and pains
  • Fatigue, tiredness, depression or anxiety

For some people, the symptoms develop gradually, almost unnoticed.  For others, the symptoms appear and become worse more rapidly, sometimes in association with a chest infection.

Different forms of pulmonary alveoloar proteinosis

There has been a tremendous advance in the understanding of PAP over the past decade and it is likely that the picture will soon become much clearer.  It is now recognised that there are several distinctly different forms of PAP, all of which are very rare and include:

  • Primary PAP 
  • Secondary PAP
  • Congenital PAP

Of these rare diseases, primary or ‘idiopathic’ PAP is the most typical and the most common form.  Idiopathic means ‘cause unknown’.

In patients with secondary PAP it is possible to identify a specific factor that actually caused the condition, such as:

  • Some cancers such as leukaemia or lung cancer
  • Massive inhalation of some particular types of dust or fumes
  • Some lung or even non-lung infections.

Congenital PAP is extremely rare and is caused by a genetic disorder

How is PAP diagnosed?

People with the above symptoms may visit their GP and in some cases the severity of their symptoms means that they are referred for tests at a local hospital.  If symptoms are milder, the GP may recommend healthy lifestyle changes (such as stopping smoking) to see if this makes an improvement.  If there is no improvement then a referral to hospital is made.

Where can I get more information about PAP?

Patients in the USA, motivated by their own experiences and frustrations, have established the Pulmonary Alveolar Proteinosis Foundation with the aims of providing support to patients (and relatives/carers), making information available about PAP and raising quality of care issues. The PAP Foundation is always happy to hear from individuals with PAP and their relatives/carers and its members are keen to provide whatever support they can.  The website includes telephone and e-mail contact details and many useful links.

Pulmonary alveolar proteinosis tests

X-rays are the initial test used to detect pulmonary alveolar proteinosis. If the results are abnormal, your doctor will normally carry out more specialist lung investigations, such as a ...


A bronchoscopy is a procedure where a doctor can look at the trachea (windpipe), the bronchi (branches of the airways) and into some areas of the lungs.

Pulmonary alveolar proteinosis treatment

A number of treatment options can be considered for pulmonary alveolar proteinosis, including physiotherapy and various ‘cough medicines’, washing the lungs and medication.

Useful contacts

If you have any queries about the information provided on these pages or would like to know more, please contact Dr Cliff Morgan, Lead Clinician - Critical Care/Consultant Anaesthetist, on 020 7351 8526.

Referral to Royal Brompton Hospital

Pulmonary alveolar proteinosis (PAP) is a rare condition affecting only around one person in every ten million.  As a result, few doctors will have any actual experience in managing the condition, meaning most patients will be immediately referred to a specialist centre.  Even some specialist centres have limited experience of the condition or see only a small number of patients with PAP. 

However, because of our expertise in lung conditions, a large proportion of English patients with PAP have been referred to Royal Brompton Hospital over several decades.  As a result, our dedicated team of clinicians has gained valuable experience of the condition.

What happens on referral to Royal Brompton Hospital?

The doctor making the referral contacts a member of our team, which includes:

  • Dr Cliff Morgan – a consultant in critical care and anaesthesia who performs most of the lung lavage treatments
  • Professor Athol Wells – a consultant in respiratory medicine and lead for the interstitial lung diseases unit, he coordinates the general medical care of patients with PAP.

When a referral is made, we look at the results of tests and any other procedures you have already had.  In some cases, we will repeat tests or conduct new ones, or ask your local hospital to do so for us. 

If it looks likely you do have PAP then we will invite you to Royal Brompton Hospital to:

  • attend our outpatient clinic for an appointment lasting approximately three hours
  • come into hospital as a planned admission for tests and first treatment lasting approximately three days.

In deciding which kind of appointment to make we will take your own circumstances, including how far you will need to travel, into account.

Outpatient appointments

These will allow you to meet our doctors and to find out more about your test results and PAP.

Planned admission

If you do need treatment for PAP then you will need to be admitted to Royal Brompton Hospital.  

It is most likely you will be treated on Elizabeth ward, where our staff have enormous experience in the nursing and care needs of PAP patients.