@article {Samhouri00527-2020, author = {Bilal F. Samhouri and Natalya Azadeh and Thorvardur R. Halfdanarson and Eunhee S. Yi and Jay H. Ryu}, title = {Constrictive Bronchiolitis in Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia}, elocation-id = {00527-2020}, year = {2020}, doi = {10.1183/23120541.00527-2020}, publisher = {European Respiratory Society}, abstract = {Background Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is characterised by multifocal proliferation of neuroendocrine cells and belongs in the spectrum of pulmonary neuroendocrine tumors. 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{\textquoteright}s electronic medical records for biopsy-proven cases of DIPNECH. We extracted clinical, pulmonary function, imaging and histopathologic data along with treatments and outcomes.Results Among 44 patients with DIPNECH 91\% were female and median age was 65 years (IQR: 56{\textendash}69 years); 73\% were never smokers. 38 patients (86\%) had respiratory symptoms including cough (68\%) and dyspnea (30\%); 45\% were previously diagnosed to have asthma or COPD. Pulmonary function testing showed an obstructive pattern in 52\%, restrictive pattern 11\%, mixed pattern 9\%, nonspecific pattern 23\%, and normal 5\%. On chest CT scan, 95\% manifested diffuse nodules and 77\% manifested mosaic attenuation. For management, 25\% of patients were observed without pharmacologic therapy, 55\% received an inhaled bronchodilator, 41\% received an inhaled corticosteroid, 32\% received octreotide; systemic steroids, azithromycin, or combination chemotherapy was employed in 4 patients (9\%). Of 24 patients with follow-up PFT available, 50\% remained stable, 33\% worsened and 17\% improved over a median interval of 21.3 months (IQR: 9.7{\textendash}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 pharmacologic therapy.FootnotesThis manuscript has recently been accepted for publication in the ERJ Open Research. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJOR online. Please open or download the PDF to view this article.Conflict of interest: Dr. Samhouri has nothing to disclose.Conflict of interest: Dr. Azadeh has nothing to disclose.Conflict of interest: T.R. Halfdanarson reports advisory boards (money paid to institution) for Advanced Accelerator Applications and Ipsen, personal fees for advisory boards from Curium and ScioScientific, and research support from Ipsen, outside the submitted work.Conflict of interest: Dr. Yi has nothing to disclose.Conflict of interest: Dr. Ryu has nothing to disclose.}, URL = {https://openres.ersjournals.com/content/early/2020/09/17/23120541.00527-2020}, eprint = {https://openres.ersjournals.com/content/early/2020/09/17/23120541.00527-2020.full.pdf}, journal = {ERJ Open Research} }