Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an extremely rare pulmonary disorder at the benign end of the neuroendocrine cells proliferation spectrum. It is mainly seen in non-smoker middle-age females with a history of chronic cough or asthma. On imaging, it is characterised by several nodules and extensive mosaic attenuation. It is, however, recognised with increasing frequency.

Epidemiology

DIPNECH typically occurs in middle-to-late age, and there isThere may be an increased female predilection ^3,10. Most patients tend to be non-smokers¹⁰.

Clinical presentation

Most are asymptomatic, where discovery is made incidentally on thoracic imaging for an unrelated reason. Some, however, may present with symptoms such as an insidious cough, a or a slowly progressive dyspnoea, or an asthma-like presentation ^7,10.

Pathology

It is characterised by a generalised proliferation of scattered single cells, small nodules or linear proliferations of pulmonary neuroendocrine cells (enterochromaffin cells, "Kulchitsky cells") ⁹. It is sometimes considered to be a precursor to pulmonary carcinoid tumours.

Radiographic features

CT

Various features have described, each of which is non-specific on their own. These include:

• small lung nodules with: considered a lower zone and peripheral predominance: mostgenerally frequent feature ^3,4,10-4 
• ground-glass changes³
• mosaic perfusion pattern ^6,7,10-7: due to air trapping
• bronchial wall thickening ^7,10
• mucus plugging
• bronchiectasis ^3,7,10: generally mild

Treatment and prognosis

The rarity of the condition poses some clinical challenge in establishing treatment and assessing prognosis. Limited studies suggest that the condition can have a variable prognosis ranging from clinical improvement to being stable to rare clinical deterioration ⁵. Various treatment strategies have been described which include somatostatin analoguessystemic and inhaled corticosteroids, azithromycinbronchodilators, and lung transplantation ¹⁰resection.

History and etymology

The first clinical series of six cases describing DIPNECH was published by Aguayo et al. in 1992¹¹.