Obstructive Lung Disease Imitator: A Case of Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia and Review of the Literature

Abstract

SESSION TITLE: Lung Pathology 2 SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare disease with approximately 100 cases found in a literature review. It is thought to be a pre-neoplastic lesion and up to 53% associated with peripheral carcinoid tumors at the time of diagnosis. CASE PRESENTATION: A 71 year-old non-smoking female was referred to a pulmonary physician for management of worsening dyspnea and non-productive cough thought to be asthma. There was no purulent phlegm, hemoptysis or other constitutional symptoms. No toxic exposures. Her physical exam was remarkable for a paucity of positive findings other than mild kyphosis. Initial CT of the chest demonstrated sub centimeter peripheral nodules and bilateral lower lobe ground glass changes. 10 months later CT showed improvement in the ground glass findings and stable nodules. Month 16 there was increased interstitial pneumonitis. The nodules remained stable. PFT’s showed mild irreversible obstruction, reduced lung volumes and a moderate reduction in the DLCO. Allergy testing, expanded chemistries and a rheumatology panel were unremarkable. Video assisted thoracoscopic wedge resection was done. The patient tolerated the procedure well. The specimen revealed multiple carcinoid tumorlets immunostaining Chromogranin, Synapthphysin, CD56 and CAM 5.2 (dot like) positive, Ki67 was low (<1%) confirming DIPNECH. DISCUSSION: DIPNECH is a histopathological diagnosis described as neuroendocrine cell proliferation initially confined to airway mucosa in small bronchi and bronchioles. It is seen as diffuse proliferation of scattered neuroendocrine cells, lines and small nodules beneath normal bronchiolar cells. Extra luminal masses are classified as tumorlets (<5mm) / carcinoid (>5mm). Even though this diagnosis is pathological, the increase number of diagnoses has been accounted to high-resolution CT detecting nodules. DIPNECH presents with nonproductive cough and dyspnea. Symptoms and lung function tests can be misinterpreted as obstructive lung disease (OLD). Asthma and COPD are often diagnosed in patients presenting with this condition. OLD symptoms are hypothesized to correlate with peptide secretory substances. Though most patients have a stable disease course these peptides are proposed to be the mechanism causing worsening respiratory function. They cause irritation, stimulate fibroblast, bronchoconstriction and chemotaxis of airway. DIPNECH is usually benign, however once confirmed a co-existing peripheral carcinoid tumor should always be ruled out in these patients. CONCLUSIONS: Although the clinical presentation of DIPNECH is usually benign, one should keep in mind this differential for patients presenting with cough, dyspnea and nodules on radiographic imaging. Reference #1: Ofikwu G, Mani VR, Rajabalan A, Adu A, Ahmed L, Vega D. A Rare Case of Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia. Case Rep Surg. 2015: 318175 DISCLOSURE: The following authors have nothing to disclose: Frances Puello, Janine Harewood, Christopher Lee, Nora Morgensten, Andrew Nguyen, Jack Mann No Product/Research Disclosure Information