What is pulmonary amyloidosis?
Amyloidosis is a group of rare conditions in which proteins fold abnormally and collect in tissues as insoluble deposits called amyloid. When these deposits form in the airways, lung tissue or pleura, the condition is called pulmonary amyloidosis.
Amyloid in the lungs can be localised, affecting only the respiratory tract, or part of systemic amyloidosis, which also involves organs such as the heart, kidneys, nerves and liver. Telling these apart is the most important step in management, because systemic disease needs urgent treatment of its cause.
Care is coordinated with haematology, cardiology and nephrology as needed, and with interventional pulmonology for airway disease.
Types of pulmonary amyloidosis
- Nodular amyloidosis: one or more nodules in the lung, often found incidentally and frequently mistaken for cancer. It is usually localised and slow-growing.
- Tracheobronchial amyloidosis: deposits in the windpipe and large airways that can narrow them. This form is usually localised.
- Diffuse alveolar-septal amyloidosis: widespread deposits in the walls of the air sacs. This form is usually part of systemic AL amyloidosis and is often accompanied by heart involvement.
Amyloid can also cause pleural effusions, enlarged lymph nodes in the chest, and lung cysts, the last particularly in association with Sjogren's syndrome.
Symptoms
Nodular disease often causes no symptoms. Other forms may cause:
- Breathlessness, gradual or progressive
- Persistent cough
- Wheeze or noisy breathing (stridor) when the large airways are narrowed, often misdiagnosed as asthma
- Coughing up blood
- Hoarse voice when the larynx is involved
- Recurrent chest infections from airway blockage
Features of systemic amyloidosis include ankle swelling, frothy urine, numbness in the hands or feet, an enlarged tongue, easy bruising around the eyes and unexplained weight loss.
Causes and associated conditions
Most lung amyloid is of the AL (light chain) type, produced by an abnormal clone of plasma cells. In localised disease the clone sits within the lung itself, while in systemic disease it is in the bone marrow, sometimes as part of myeloma. Other associations include Sjogren's syndrome, low-grade lymphoma of the lung (MALT lymphoma) and, less commonly, AA amyloidosis due to long-standing inflammatory disease or chronic infection such as untreated bronchiectasis or tuberculosis. Hereditary and age-related transthyretin (ATTR) amyloid mainly affects the heart rather than the lungs.
How pulmonary amyloidosis is diagnosed
Diagnosis requires tissue showing amyloid, followed by tests to identify its type and whether it is systemic.
| Test | What it shows |
|---|---|
| CT chest | Nodules, airway wall thickening, diffuse changes, often with calcification |
| Bronchoscopy | Direct view of airway deposits and biopsy |
| Biopsy with Congo red staining | Confirms amyloid under polarised light |
| Amyloid typing | Identifies the protein type, which guides treatment |
| Serum free light chains and protein electrophoresis | An abnormal plasma cell clone |
| Echocardiogram, cardiac MRI, urine protein | Heart and kidney involvement in systemic disease |
Bronchoscopy is central for airway disease. Biopsy of amyloid can bleed more than usual, so it is planned carefully.
Treatment
Localised disease
Isolated nodules without symptoms are often simply monitored, or removed surgically if the diagnosis is uncertain. Tracheobronchial amyloidosis causing narrowing is treated with interventional bronchoscopy (removal of deposits, laser or argon plasma treatment, balloon dilatation or stents), and external beam radiotherapy can reduce recurrence in selected patients.
Systemic AL amyloidosis
Systemic disease is treated by haematology with therapy directed at the plasma cell clone, typically based on bortezomib and daratumumab combined with other agents, and in suitable patients high-dose chemotherapy with stem cell support. The aim is to stop new amyloid forming so that organs can recover.
Other forms
AA amyloidosis is managed by controlling the underlying inflammation or infection.
Outlook and follow-up
Localised nodular amyloid usually has an excellent outlook. Airway disease is slow but tends to recur, needing repeat bronchoscopic treatment over years. The outlook in systemic AL amyloidosis depends mainly on heart involvement and response to treatment, which has improved considerably with modern therapy. Follow-up includes lung function, imaging, bronchoscopy for airway disease, and blood tests to check that localised disease has not become systemic.
When to seek urgent care
Seek emergency care for noisy or difficult breathing (stridor), coughing up more than a small amount of blood, breathlessness at rest, fainting, chest pain or palpitations. These may indicate critical airway narrowing, bleeding or heart involvement.
Frequently asked questions
Is pulmonary amyloidosis a cancer?
Amyloidosis is not itself a cancer, but most lung amyloid is produced by a small abnormal population of plasma cells. In some patients this is linked to lymphoma or myeloma, which is why full assessment is needed.
Does amyloid in the lung mean it is in other organs too?
Not necessarily. Nodular and airway amyloid are usually localised to the lungs. Blood, urine and heart tests are done to check whether the disease is systemic.
Can amyloid deposits be removed?
Airway deposits can be cleared through interventional bronchoscopy, and isolated nodules can be removed surgically. Widespread deposits in lung tissue cannot be removed directly. Treatment targets their source.
Why was I treated for asthma first?
Airway amyloidosis narrows the windpipe and bronchi, causing wheeze and breathlessness that can resemble asthma. Poor response to inhalers is one clue that prompts further investigation.
Will I need lifelong follow-up?
Yes. Airway amyloid can recur, and monitoring ensures that any systemic disease is detected early.
Related conditions and procedures
Consult Dr. Gogineni Ratnakara Rao
Apollo Hospitals, Financial District: Monday to Saturday, 8:30 AM to 5:00 PM. Anything in Lung Clinic, Chanda Nagar: Monday to Saturday (Thursday closed), 6:00 PM to 9:00 PM.