Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia

Dr Henry Knipe and Dr Yuranga Weerakkody et al.

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 characterized by several nodules and extensive mosaic attenuation. It is, however, recognized with increasing frequency.

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

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, slowly progressive dyspnea, or an asthma-like presentation 7,10.

DIPNECH is diffuse neuroendocrine cell hyperplasia of the peripheral airways, forming scattered single cells, small nodules, or linear proliferations confined to the airway mucosa. It may be associated with fibrosis or chronic inflammation 14. Therefore, DIPNECH may cause bronchiolar occlusion and constrictive bronchiolitis 13.

It is considered a precursor to the development of carcinoid tumorlets (nodular aggregates that measure less than 5 mm and invade the adjacent basement membrane) or carcinoid tumor (cells aggregates of 5 mm or more and demonstrate invasive growth 12.

A reactive pulmonary neuroendocrine cell hyperplasia related to hypoxia or lung injury have also been described and is considered a different entity. DIPNECH is reserved only for cases in which hyperplasia is an idiopathic condition 12.

The constrictive bronchiolitis is responsible for the radiographic features. DIPNECH manifests as multifocal bilateral pulmonary micronodules (cells clusters) and extensive mosaic attenuation due to air trapping and constrictive bronchiolitis on expiratory CT images 13. Bronchial wall nodular thickening (cell clusters), mucus plugging and bronchiectasis are also frequent features 13.

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 analogs, azithromycin, and lung transplantation 10.

The first clinical series of six cases describing DIPNECH was published by Aguayo et al. in 1992 11.

Chest

Article information

rID: 20656
System: Oncology, Chest
Synonyms or Alternate Spellings:
  • Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH)
  • DIPNECH

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Cases and figures

  • Case 1
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  • Case 2: with probable carcinoid
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  • Case 3
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