Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) refers to proliferation of pulmonary neuroendocrine cells within the walls of airways. It may remain confined to the mucosa as cellular aggregates (preinvasive stage), or invade across the basal lamina to form tumorlets or carcinoids that extend into adjacent lung parenchyma. Nodular or papillary aggregates of pulmonary neuroendocrine cells may protrude into the bronchial lumen causing mucus plugging, airway obstruction, air-trapping, and bronchiectasis. Usually, there is chronic inflammatory infiltrate nearby along with peribronchiolar fibrosis which sometimes results in obliterative bronchiolitis. Two aggregate of pulmonary neuroendocrine cells can be seen in this image at 3 and 9 o'clock positions.