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A6519 - DIPNECH: A Lung Lined by Tumor
Author Block: H. Tavakoli1, J. Patel2, M. Bhargava3; 1Internal Medicine, Internal Medicine, Oakland, CA, United States, 2Pulmonary and Critical Care Medicine, California Pacific Medical Center, San Francisco, CA, United States, 3Internal Medicine - Pulmonary and Critical Care Medicine, Oakland, CA, United States.
Introduction: Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia (DIPNECH) is a rare, indolent, and poorly understood lung disease characterized by abnormal proliferation of neuroendocrine cells in the respiratory bronchioles. Most patients are asymptomatic, contributing to a delay in diagnosis. Radiographic features may precede symptoms and include mosaic attenuation due to small-airway air trapping, bronchial wall thickening, and bronchiectasis.
Case Report: A 68-year-old woman with hypertension, severe aortic stenosis, and obstructive sleep apnea was referred to Pulmonology Clinic for evaluation of chronic non-productive cough for 10 years. She was previously diagnosed with allergic rhinitis with cough from post-nasal drip. She failed outpatient therapy and was later diagnosed with severe-persistent asthma and initiated on maximal inhaled therapy including long-acting beta agonists/inhaled corticosteroids, omalizumab, and leukotriene receptor antagonists. Her symptoms, nevertheless, persisted and further workup implicated her aortic stenosis as the probable cause of her symptoms. Exam was notable for an obese female with intermittent loud dry cough. A prominent systolic murmur was heard at the left upper sternal border. Lungs revealed diminished air exchange bilaterally with trace basilar end-inspiratory crackles. Pulmonary function tests revealed a mixed restrictive and obstructive disease pattern. High-resolution computed tomography showed multiple scattered bilateral, subcentimeter micronodules, mild bronchiectasis, and extensive mosaic attenuation. A comprehensive laboratory workup for interstitial lung disease did not elucidate an etiology. A Positron Emission Tomography scan revealed diffuse mildly hyperactive micronodules prompting lung biopsy to rule out malignancy. She underwent transthoracic core biopsy of the largest lung nodule (8mm). Pathology showed neoplastic cells in trabecular nesting arrangement. Immunohistochemical staining revealed small tumorlets of neuroendocrine cells, consistent with DIPNECH, a precancerous carcinoid neoplasm. The patient underwent Transcatheter Aortic Valve Replacement with modest improvement in her cough. A follow-up CT showed persistent diffuse innumerable lung nodules with mosaic attenuation suggesting no significant change.
Discussion: The combination of multiple pulmonary nodules with features of patchy ground-glass attenuation with mosaicism in a non-smoker, middle-aged female presenting with chronic cough and wheezing should raise suspicion for DIPNECH. Diagnosis is often delayed due to the disease's indolent nature; however, concomitant cardiopulmonary conditions may exacerbate symptoms and prompt an expedited workup. Definitive management of these co-morbid conditions may partly alleviate symptoms, although do not affect progressive small airways disease. Although surgical lung biopsy is recommended for diagnosis, this case illustrates that transthoracic biopsies may be considered when surgery is not a viable option.