Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia with multiple synchronous carcinoid tumors.

The spectrum of pulmonary neuroendocrine cell proliferation ranges from reactive hyperplasia to small cell carcinoma and includes diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. A case is reported and features of this disease are described according to the published evidence. The entity was first included in the WHO classification of tumors in 1999 and is considered a preneoplastic condition for carcinoid tumors. Patients generally report slowly progressive dyspnea and cough, and have airflow obstruction, multiple pulmonary nodules and/or radiological signs of air trapping, although asymptomatic cases with normal pulmonary function have been described. Histologically, it is characterized by neuroendocrine cell proliferation in the airway epithelium, in most cases beyond the basal membrane forming tumorlets and carcinoid tumors that are frequently multiple. The prognosis is favorable in most cases.