Pulmonary Pathology Online
Pathology of Diffuse Idiopathic Neuroendocrine Cell Hyperplasia (DIPNECH)
idiopathic neuroendocrine cell hyperplasia (DIPNECH) is a preneoplastic lesion
for pulmonary carcinoid tumours.
DIPNECH is a very rare lesion.
DIPNECH is characterized by :
(i) generalized proliferation of scattered single cells,
(ii) small nodules (neuroendocrine bodies), or
(iii) linear proliferations of pulmonary neuroendocrine (NE) cells.
The cells seen in the NE cell proliferation of DIPNECH are similar to those found in the normal lungs of adults.
Age and sex : Usually presents in the fifth or sixth decades of life. There appears to be a female predominance.
Clinical presentation: Patients present with slowly progressive dry cough and dyspnea.
Diagnostic tests: Pulmonary function tests show an obstructive or mixed
obstructive/restrictive pattern of impairment with reduced diffusing
Computerized tomographic scanning demonstrates a mosaic pattern of air trapping, sometimes with nodules and thickened bronchial and bronchiolar walls.
Patients with DIPNECH typically have a favourable clinical course.
Rare patients have required lung transplantation due to severe obstructive airway disease.
The carcinoid tumors that occur in DIPNECH so far have all been typical carcinoids.
DIPNECH usually affects one or both lungs diffusely.
- The lung demonstrates extensive proliferation of NE cells.
- NE cell hyperplasia consists of increased numbers of individual cells, small clusters (or NE bodies), or linear arrays of NE cells.
- The bronchiolar wall sometimes is fibrotically thickened and the airway lumens may be constricted or occluded either due to fibrosis and/or NE cell proliferation.
- The diagnosis of DIPNECH requires exclusion of inflammatory
or fibrous airway lesions that might cause a secondary NE cell
Differential diagnosis includes NE cell hyperplasia and or tumorlet that can occur as a secondary lesion in a wide variety of inflammatory and fibrotic lung conditions such as bronchiectasis and chronic lung abscess.
DIPNECH must also be distinguished from the NE cell hyperplasia that can be seen in the normal lung adjacent to up to 75% of peripheral carcinoid tumors.
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