Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia: Review of the Literature and a Single-center Experience

Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia (DIPNECH) Progressing to Carcinoid Tumor: A Case of Chronic Cough

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH), a rare disease previously overlooked, is gradually being recognized as an important precursor state to pulmonary neuroendocrine tumors. The very insidious onset of symptom presentation makes early diagnosis of DIPNECH almost impossible in clinical settings. In this report, we present a case of persistent and worsening cough for over five years with waxing and waning lung nodules of varying sizes which were eventually diagnosed as DIPNECH on biopsy. However, due to the location and the multiplicity of these nodules, surgical resection was not an option in this case. The diagnostic workup including imaging and biopsy, management options, and possible prognosis of DIPNECH are discussed in detail. This report highlights the growing recognition of DIPNECH as a clinical entity to be aware of during the formulation of a differential diagnosis for patients presenting with chronic unrelenting cough and associated lung nodules.

Constrictive bronchiolitis in diffuse idiopathic pulmonary neuroendocrine cell hyperplasia

Background

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is characterised by multifocal proliferation of neuroendocrine cells and belongs in the spectrum of pulmonary neuroendocrine tumours. Some patients with DIPNECH develop airflow obstruction but the relationship between the two entities remains unclear.

Methods

We performed a computer-assisted search of the Mayo Clinic's electronic medical records for biopsy-proven cases of DIPNECH. We extracted clinical, pulmonary function, imaging and histopathological data along with treatments and outcomes.

Results

Among 44 patients with DIPNECH 91% were female and the median age was 65 years (interquartile range 56–69 years); 73% were never-smokers. Overall, 38 patients (86%) had respiratory symptoms including cough (68%) and dyspnoea (30%); 45% were previously diagnosed to have asthma or COPD. Pulmonary function testing showed an obstructive pattern in 52%, restrictive pattern in 11%, mixed pattern in 9%, nonspecific pattern in 23%, and was normal in 5%. On chest computed tomography scan, 95% manifested diffuse nodules and 77% manifested mosaic attenuation. For management, 25% of patients were observed without pharmacological therapy, 55% received an inhaled bronchodilator, 41% received an inhaled corticosteroid, 32% received octreotide; systemic steroids, azithromycin, or combination chemotherapy was employed in four patients (9%). Of 24 patients with available follow-up pulmonary function tests, 50% remained stable, 33% worsened and 17% improved over a median interval of 21.3 months (interquartile range 9.7–46.9 months).

Conclusion

DIPNECH occurs mostly in women and manifests diffuse pulmonary nodules and mosaic attenuation on imaging. It is commonly associated with airflow obstruction due to constrictive bronchiolitis, which manifests limited response to current pharmacological therapy.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an under-recognised cause of obstructive lung disease in women. Constrictive bronchiolitis associated with DIPNECH manifests limited response to currently employed therapies.https://bit.ly/3c3RZoe