What is DIPNECH?
DIPNECH stands for diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. The lining of the airways contains a small number of specialised neuroendocrine cells, which release chemical messengers. In DIPNECH these cells multiply throughout both lungs, without a known cause. They can form small clusters called tumourlets and, in some people, slow-growing carcinoid tumours.
The World Health Organization classifies DIPNECH as a pre-invasive lesion for carcinoid tumours of the lung. That sounds alarming, but in most patients the condition behaves slowly over many years, and the main problem is chronic cough and breathlessness caused by narrowing and scarring of the small airways (constrictive bronchiolitis).
DIPNECH is rare and is diagnosed mainly in middle-aged and older women, many of whom have never smoked. It is increasingly recognised as more CT scans are performed.
Symptoms of DIPNECH
Symptoms usually develop gradually over years:
- Chronic dry cough: the commonest symptom, often persisting despite treatment.
- Breathlessness on exertion: slowly progressive.
- Wheeze, which frequently leads to a diagnosis of asthma that does not respond well to standard inhalers.
- No symptoms: some people are diagnosed after multiple small nodules are seen on a scan done for another reason.
The hormone-related symptoms seen with some neuroendocrine tumours, such as flushing and diarrhoea, are uncommon in DIPNECH.
Causes and risk factors
The cause is unknown, which is what idiopathic means. DIPNECH is not caused by smoking, infection or occupational exposure, is not contagious, and is not known to be inherited. The narrowing of the small airways is thought to result from the neuroendocrine cells and the substances they release, which promote scarring around the bronchioles.
It should be distinguished from neuroendocrine cell increases that occur as a reaction to other lung diseases, such as chronic inflammation or scarring, which are not DIPNECH.
How DIPNECH is diagnosed
A long delay before diagnosis is common. The combination of persistent cough or wheeze, multiple small lung nodules and a CT pattern of air trapping in a woman who has never smoked should raise the possibility.
| Test | What it shows |
|---|---|
| High-resolution CT with expiratory images | Multiple small nodules in both lungs and a patchy mosaic pattern with air trapping |
| Lung function tests | Obstructive or mixed pattern, sometimes normal in early disease |
| Lung biopsy | Proliferation of neuroendocrine cells confirmed with special stains such as chromogranin and synaptophysin |
| Somatostatin receptor PET-CT | Used selectively to assess larger nodules for carcinoid tumour |
| Serum chromogranin A | Sometimes raised, but not reliable on its own |
Biopsy is usually needed to confirm the diagnosis. Tissue may come from surgical removal of a nodule, a video-assisted surgical lung biopsy, or in selected cases bronchoscopic cryobiopsy. Biopsy findings are reviewed by a pathologist with experience in lung neuroendocrine lesions.
Treatment
There is no established cure and no treatment approved specifically for DIPNECH, so management is individualised and coordinated with oncology and thoracic surgery.
Symptom control
Inhaled bronchodilators and inhaled corticosteroids help some patients with cough and wheeze, though responses are often partial. Somatostatin analogues such as octreotide or lanreotide have improved cough and breathlessness in reported series and are considered for troublesome symptoms. Macrolide antibiotics are sometimes used for their anti-inflammatory effect. Systemic corticosteroids are generally not helpful in the long term.
Managing nodules and carcinoid tumours
Small nodules are monitored with periodic CT scans. A nodule that grows, or that reaches the size of a carcinoid tumour, may be removed surgically with lung-sparing surgery where possible. mTOR inhibitors such as everolimus are used for more advanced neuroendocrine tumours and are being studied in DIPNECH.
Advanced disease
In the small number of patients with severe progressive airway disease, assessment for lung transplantation may be considered.
Outlook and follow-up
Most people with DIPNECH have a stable or very slowly progressive course, and life expectancy is generally good. Lung function may remain steady for many years. Follow-up usually includes lung function testing and CT surveillance of nodules at intervals agreed with the specialist team, adjusted according to how stable the scans are. Avoiding smoking, staying active and receiving influenza and pneumococcal vaccines support long-term lung health.
When to seek urgent care
Seek urgent medical attention for sudden worsening of breathlessness, breathlessness at rest, coughing up blood, chest pain, high fever with breathing difficulty, or blue lips. A rapid change in symptoms should not be assumed to be part of DIPNECH and needs assessment.
Frequently asked questions
Is DIPNECH a cancer?
DIPNECH itself is not a cancer, but it is classified as a pre-invasive lesion because some people develop carcinoid tumours, which are low-grade neuroendocrine tumours. Most carcinoids in DIPNECH grow slowly, and regular CT monitoring allows them to be detected and treated early.
Why was I told I had asthma?
DIPNECH causes cough, wheeze and breathlessness, which closely resemble asthma. Clues that it may be something else include multiple small lung nodules on CT, air trapping, and a poor response to asthma inhalers.
Do I need a lung biopsy?
A biopsy is usually needed to confirm the diagnosis and to rule out other conditions with nodules, such as metastatic cancer or infection. The type of biopsy depends on the size and location of the nodules.
How often will I need scans?
CT scans are repeated at intervals decided by your specialist, often more frequently at first and then less often if the nodules remain stable.
Can DIPNECH be cured?
There is currently no cure, but symptoms can often be improved, and the condition progresses very slowly in most people. Individual carcinoid tumours can be removed if needed.
Will my family be affected?
DIPNECH is not known to be inherited, and family members do not usually need screening.
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.