Abstract Introduction/Objective Congenital pulmonary airway malformations (CPAM) is rare, usually diagnosed in the pediatric population, and may occur in adults. Pulmonary neuroendocrine cell hyperplasia (PNECH) mimicking diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) associated with CPAM has not been described previously. We report a case of CPAM Type 1 with PNECH. Methods/Case Report A 33-year-old male, with past medical history of latent tuberculosis (TB) by Quantiferon blood testing, recurrent pneumonia, recurrent lung abscesses, and lung cavitary lesion for three years, presented with fever, cough with hemoptysis, shortness of breath, and left-sided chest pain. Computerized tomography of chest displayed a 10.8 cm cavitary lesion in the left lower lobe of the lung. The patient underwent left lower lobectomy of the lung. Grossly, the lobectomy specimen revealed a 10.5 cm irregular cavity communicating to the superior segmental bronchus of the left lower lobe. Microscopically, the dominant large cyst was surrounded by lung parenchyma and small cystically dilated spaces resembling bronchioles under the fibrotic pleura. The large cyst was lined by respiratory epithelium with rare pathognomonic mucous cells in clusters. Cyst walls contained smooth muscle, small islands of cartilage, and focal intense acute and chronic inflammatory cell infiltrates with hemorrhage. There were multiple foci of proliferation of pulmonary neuroendocrine cells centered around bronchioles surrounding the large cyst. The neuroendocrine cells were arranged from individual cells and cellular aggregates to larger tumorlets, highlighted by Synaptophysin and Chromogranin immunostains. No granuloma or necrosis was present. No acid-fast bacilli or fungal microorganisms were identified by special stains. The findings are consistent with CPAM type 1, with PNECH. Results (if a Case Study enter NA) NA Conclusion Our study demonstrates a histologically diagnosed adult congenital pulmonary airway malformations type 1 with an incidental pulmonary neuroendocrine cell hyperplasia, which mimics diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. To the best of our knowledge, this is the first report of such an association.