What is NEHI?
Neuroendocrine cell hyperplasia of infancy (NEHI) is a rare disorder of the lungs that was first described and classified in 2005. NEHI is a sub-group of Children’s interstitial lung disease (chILD) that typically presents within the first two years of life.
What causes NEHI?
At this time the cause of NEHI remains unclear and requires further investigation. Clinical studies and medical research suggest that restriction of the distal airways leads to air trapping in the lungs, but the mechanism is poorly understood. Families known to have multiple NEHI children are a strong indicator of a genetic basis for this disorder.
What are the symptoms?
What are the symptoms?
Children with NEHI present common but challenging clinical features that are often misdiagnosed as more common lung diseases found in children. These clinical features include: respiratory distress (tachypnea, exercise intolerance), hypoxemia (low levels of oxygen in the blood), failure to thrive, retractions, and a crackling sound upon inhalation observed with a stethoscope.
How is NEHI diagnosed?
The road to a NEHI diagnosis can look very different for every patient. Initially most patients will have lab work and a bronchoscopy performed to look for more common lung disorders. Once a form of chILD is suspected a chest CT is often the next step. NEHI has a distinct geographic pattern of ground-glass opacities on CT images. The scan can also show a mosaic pattern that is created by overinflated and underinflated areas of the lungs. An Infant Pulmonary Function Test (infant PFT) is another tool used in diagnosis. Although not readily available at all facilities a PFT can be an important piece of the diagnostic process because it can show trapping of air in the lungs, which is one of the key characteristic of NEHI. Historically a lung biopsy was the gold standard for NEHI diagnosis. The lung tissue is treated with bombesin stain that will bind with pulmonary endocrine cells (PNECs) to make them more visible for inspection. NEHI patients will show an abnormally large number of PNECs within the small (distal) airways. At this time it’s not understood if the increased number of PNECs is a contributing factor to NEHI symptoms or merely a marker for the disease. Recently the American Thoracic Society published clinical guidelines now recommending noninvasive diagnosis of NEHI based on computed tomographic (CT) chest imaging finding and clinical findings.
As seen on CT scan. Image courtesy Wikipedia.
Neuroendocrine cells stained brown in this thin section of biopsied lung tissue.
What treatment options exist?
The treatment for NEHI is primarily supportive. Low oxygen saturation is common among NEHI patients and often requires the use of supplemental oxygen. The flow rate and duration of oxygen use is different for every patient but may vary from 24 hours a day, while sleeping, or only when ill (especially respiratory infections or irritations). Oxygen requirements tend to decrease with age, although there are many patients who after months or years without supplementary oxygen will begin requiring it again for short or long term. Whether in conjunction with illness or seemingly random, these times of increased symptoms and potential oxygen needs are referred to as NEHI exacerbations.
What does the future hold for NEHI patients?
Due to NEHI being a relatively “young” disease (first recognized in 2005) the patient population is both young and low in numbers. Given the limited data, the long-term prognosis for NEHI remains unclear. As the number of patients diagnosed with NEHI grows and as those already diagnosed mature, so will the knowledge about the future of NEHI. It is important to note that there are currently no known fatalities directly associated with NEHI.